The Wii Balance Board measures shifting weight.

For the past eight days, I’ve been stretching, crunching, yoga-posing and even running using this $90 package from Nintendo (NTDOY.PK). Wii Fit is the title of the disc that comes with the Wii Balance Board, a sturdy platform on which you perform your routines. The two are used together for various types of yoga, strength training, aerobics and balance games, which involve the Wii game system’s “Miis” — on-screen representations of yourself — that interact with trainers and other virtual characters. Sensors in the Balance Board detect a user’s weight, body mass index, balancing skills and positioning during activities, and the Wii Fit program keeps track of this information, providing tips on technique or weight loss. Wii Fit and the Balance Board must be used with the original Wii system, which costs $250.

I’ve grown fond of using Wii Fit and the Balance Board because it holds me accountable for my weight and balance skills. I learned fitness and health tips from a small, animated image of the Balance Board that jumped around on-screen — such as the fact that people who cross their legs while sitting are more likely to have back problems. And after a few days of using the system, I could feel a difference in my muscles.

For those used to 30-to-40-minute workout sessions, the Wii Fit programs may seem lightweight, since activities last for only about three to five minutes each. To unlock longer activities or additional strength-training repetitions, you must first do them a handful of times in their short versions, which can be frustrating. Nintendo says this is designed so that average users don’t feel intimidated, but I felt like some of the activities ended just as I was getting into them. Almost all activities involve actually standing on or touching the board.

Motivation is a key element in the Wii Fit programs. An on-screen graph tracked my progress, and I “stamped” each calendar day to show that I had exercised. Each minute of activity added a point to my Fit Bank, and enough points unlocked new activities; Wii Fit includes over 40 altogether. On-screen instructors demonstrated and joined me during yoga and strength-training exercises, congratulating me when I held my balance or noting that I stopped mid-exercise.

A daily body test measured my weight and body mass index against those from previous days and challenged me to two short balance tests, which changed daily. After, I was told my Wii Fit Age, a number reached using my actual age, BMI and performance on the balance tests. On good days this number was a couple of years below my real age, but it drifted upward when I was given harder tests, sometimes reaching 13 years older than my actual age.

Top: Wii Fit charts fitness progress over time, including body mass index and weight. Yoga (middle) and balance games like Ski Slalom (bottom) mirror board movements.

More than one person can use the system and profiles can be password protected. Friends can use the Balance Board under someone else’s profile; the system notices weight changes and confirms that it’s alright to continue.

The Balance Board measures roughly the size of a step used in step aerobics classes, and uses the same technology that gauges the weight of airplanes. These sensors expand and contract when someone stands on the board, measuring weight, and where and how that weight is shifting on the board. This works out of the box with four included AA batteries. Its power button can be nudged on with a foot, turning off automatically after five minutes of non-use.

I started with basic yoga, attempting the half-moon pose. I opted for a male instructor who told me that this position helped improve posture and digestion. He briefly demonstrated the position, and we got started on the actual session, which lasted two minutes. A large, on-screen circle that expanded and contracted illustrated when I should inhale and exhale as I held positions. I tried the Warrior, Tree and Sun Salutation positions throughout the week.

In the strength-training section of the program, I liked the Single-Leg Stretch exercise, which involved standing on the Balance Board on one leg and holding the other leg off the ground, bent up toward my chest. I slowly extended this bent leg out and in, while moving my arms and trying to maintain my center of balance. This exercise started at six repetitions, but increased to 10 reps as I improved; 20 reps are the maximum.

I tried the Torso Twists and Rowing Squats, but had a lot of trouble with Push Ups and Side Planks (modified push-ups), because I’m not good at push-ups. To my surprise, my trainer didn’t notice when I couldn’t finish the session. I got my best score on that exercise, clearly a flaw in the system.

During yoga and strength-training exercises, an on-screen red dot marked where my center of balance was detected, and I was encouraged to try to keep that dot within a highlighted area. After the exercise, a diagram showed where my weight had shifted, and I earned better rankings when I distributed weight evenly.

Aerobics were more fun, including hula hooping. I rotated my hips and I leaned forward so that my on-screen cartoon self could catch hoops thrown over my head by other characters. The Balance Board tracked the number of times I rotated my waist around in a circle. One aerobics activity that didn’t use the board was Basic Run, which requires users to put the Wii remote in a pocket or hold it while running in place for time intervals measuring three, five or 10 minutes depending on the pace. This mode is designed so users can either watch other runners on-screen or tune into television while running as Wii Fit tracks your progress. An aerobics activity called Basic Step was like Dance Dance Revolution: on-screen footprints showed where and how to step next — on and off the board.

Balance Games were fun — but hard. I tried a bunch, including Soccer Heading (where you pretend you’re the goalie), Ski Slalom and Tightrope Walk, and was surprised by the sensitivity of the Balance Board. But the more I played, the better I became at controlling my balance.

I brought the Wii and Balance Board with me to my parents’ house last weekend, but most people will do best to keep this board in one place since it weighs 10 pounds.

When I stepped onto the Balance Board at my parents’ house in a room with wall-to-wall carpeting, the system thought I had lost 13.4 pounds since the day before. I stepped off and tried this measurement again a few minutes later, but was told I lost another 4.6 pounds. However, when I returned to my own home with the board on an area rug on hardwood flooring, the system showed I “gained” 16.1 pounds. My weight at my own house was on the mark.

Some of my relatives jokingly saw this instant weight loss as a reason to buy a Balance Board, but this made me question the system’s accuracy.

Nintendo solved the mystery: The carpeting in my parents’ house, which I mistakenly thought was similar to the area rug in my house, must have been touching the bottom of the board, therefore transferring my weight onto the carpet and away from the board. Four circular “feet” come with the Balance Board to elevate it, solving the problem.

When the Wii Fit system thought I lost or gained a lot of weight in one day, it was concerned and offered tips for healthier fitness. In the case of the supposed weight gain, I was asked to think about why I might have gained weight, then had to select an answer from a list of reasons why, including Late Dinners, Night Snacking and Not Exercising. The system gave health tips related to the reasons.

Users’ outside exercise can be accounted for in the system. I added the time I spend playing tennis each week and this information plugged into a graph to illustrate fitness activity over time.

The idea of having a virtual trainer and a way to set weight-loss goals while tracking progress could be truly valuable for people in need of motivation without the expense and/or hassle of going to a gym. If you’re looking for a fun way to get in shape, the Balance Board will do the trick. Like the Wii, its activities encourage all sorts of people to use it, marking yet another smart move from Nintendo.

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But several companies now sell wireless mice designed especially for laptop users for whom the laptop touch pad just won’t do. These mice are small, sleek, colorful gadgets that more fashion-conscious computer users can happily show off in an airport, in a coffee shop or on campus.

See a chart comparing the three mice

This week I tested three entry-level mobile mice designed for laptops, from Logitech (LOGI), Microsoft (MSFT) and Kensington Computer Products Group. These $30 mice include a USB receiver that plugs into a laptop, allowing the mouse to work wirelessly. When not in use, this receiver fits snugly beneath the mouse, turning its power off to save battery as it snaps into place. These mice are also somewhat smaller than regular mice so they can easily slip into a laptop bag.

Mobile mice are now more stylish than the traditional desktop mice, and like laptops and digital cameras, come in various shapes and colors. The mice I tested are available in pink, white, red, blue, orange and gray. Next week, the Microsoft mouse I used will be available in shades of pomegranate, aloe, dragon fruit (dark pink) and milk chocolate; a khaki-colored shade called crème brûlée will follow in June.

I tried Logitech’s $30 V220 Cordless Optical Mouse in black, Microsoft’s $30 Wireless Notebook Optical Mouse 3000 in aloe, and Kensington’s $35 Ci75m Wireless Notebook Mouse in orange. To gain some perspective on high-end mobile mice, I also looked at two pricier options from Logitech: the $50 V470 Cordless Laser Mouse with Bluetooth (instead of a USB receiver) and the $70 VX Nano Cordless Laser Mouse.

My vote for a favorite low-end mobile mouse had me struggling between portability and comfort. But overall, I found that the Logitech V220 offered the best combination of small size and usability. The Microsoft mouse was also comfortable to use, but its slightly bulkier size made it less portable, and it didn’t feel as sturdy as the Logitech. While the Kensington was the flattest and most portable, it wasn’t as comfortable to use as the Logitech or Microsoft mice.

To conserve battery, all three of these mice go into low-power mode after 10 minutes of nonuse, but none of them turns off completely. Battery indicators light up when juice is running low. According to company estimates, the Microsoft mouse has a battery life of over six months and the Logitech mouse has a battery life of up to six months. The Kensington mouse’s battery life was estimated to be three months. I didn’t use any of them long enough to prove the company claims.

These mice are compatible with Macs and PCs, and are plug-and-play — meaning you don’t need to install any additional software to make them work. I used each on laptops running Mac OS X and Windows Vista without any problems. The Microsoft and Logitech mice also can work with their own special software programs, but the extra features, such as reassigning a mouse button to open an application, aren’t really necessary for the average user.

The $30 Logitech V220 fit comfortably in my hand, with rubber grips on its sides and a generously sized, smooth-gliding rubber scroll wheel that made it easy to use. This scroll wheel can be nudged to the left or right for horizontal scrolling, a feature found on most of Logitech’s mice.

Unlike the Microsoft and Kensington mice, which show flashing red sensor lights, the Logitech uses an invisible optic sensor. This sounds cool, but because the mouse doesn’t use any lights, it can be left on accidentally. I did this a few times before remembering to stow the USB receiver in the mouse to automatically turn off its power.

Of the three, the Logitech mouse was the only one with a manual on/off switch — so you can turn it off without snapping the USB receiver into place in the mouse. This could save frequent travelers from having to detach the USB receiver every time they want to turn off the mouse, and could let people keep the receiver plugged into the laptop.

Kensington’s $35 Ci75m was the flattest mouse by far, making it a cinch to slip it into the outside pocket of my already full laptop bag on a train trip to New York. And this mouse has a bonus feature: It can work wirelessly or with a USB wire, which wraps up inside the mouse and serves as a backup in case the mouse runs out of battery. I tested this by removing the batteries and using only the USB wire, and it worked like a charm.

I also liked the way the Kensington USB receiver disappeared into the body of the mouse, while the Microsoft and Logitech receivers protruded a bit when stowed, adding to the thickness of the mouse when tucked into a laptop pocket.

But though this bright orange mouse received approving feedback from passersby, it wasn’t all that comfortable to use after a while. Its flatness saved room in my bag, but didn’t give my hand much support. It also felt flimsier than the Logitech, and its small wheel wasn’t as satisfying to use.

I received early test units of Microsoft’s $30 Wireless Notebook Optical Mouse 3000 in aloe, pomegranate and milk chocolate.

This mouse has rubber sides for a better grip, like the Logitech, and an arched shape for comfort. Its wheel is slightly smaller than Logitech’s, though its overall size was bigger and more like that of a regular mouse — not one designed specifically for mobile use. But even though the Microsoft mouse was larger, it didn’t feel as solid as Logitech’s; rather, it felt more like the thin Kensington. Its right and left buttons felt less stable, and its wheel didn’t roll as smoothly.

I did like Microsoft’s nod to new colors, and the aloe — a cool hue of green — was my favorite.

For people who don’t mind spending a little extra money on a mouse, the $50 V470 Cordless Laser uses Bluetooth, eliminating the need for a USB receiver altogether. It took only a couple seconds to pair this mouse to a MacBook with built-in Bluetooth, and it worked smoothly. A manual on/off switch on this mouse’s underside can help to conserve battery.

The $70 Logitech VX Nano Cordless Laser is sleek with shiny black accents and a silver-edged wheel. The “Nano” in this mouse’s name refers to its ultra tiny USB receiver, which sticks out only about a quarter of an inch when plugged in, so it can be left in a laptop at all times for ease-of-use. If needed, this receiver can be hidden away in the cavity of the mouse, under a snap-on lid. I used the VX Nano to glide around Web pages and Word documents with buttery smoothness.

No matter what mouse you choose to use with your laptop, most will be considerably more comfortable than touch pads and trackpoints, especially while working on long, mouse-intensive projects. But of the three lower-end mobile mice, the Logitech V220 Cordless Optical Mouse delivers the best combination of comfort and transportability.

The chart below (click on it to make it larger) compares features of the three mice described in this column.

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But real was exactly what UGOBE Inc. had in mind when the company created this $350 baby dino named Pleo. This robot isn’t referred to as such; instead, UGOBE calls Pleo a “life form” because unlike most robots that are designed to follow a specific command or algorithm, Pleo alters its behavior as it adapts to its surroundings including sights, sounds and touch. And it’s designed to move and act in ways that seem very much like a real animal.

These responsive qualities have earned Pleo quite a bit of attention, and the two years between when the product was first announced and when it became available only added to the anticipatory hype. Now, after three delays in the past two years and numerous back orders, Pleo is available from www.pleoworld.com. (UGOBE says that many of the product’s delays were caused by trying to get Pleo’s battery just right.)

In short, I found Pleo to be a fun and interesting robot/life form. Though Pleo’s reactions and movements are endearing, many of them run together after a while with only subtle differences, especially compared with fast-paced videogames. Pleo’s tricks were entertaining early on, but, in time, many of them blended together, rarely surprising me.

Pleo’s battery is still a major drawback. It’s rechargeable, but only lasts for around an hour of active play before it must be removed and placed in a holder for three hours of recharging. This frustrating fact means you can’t turn Pleo on to roam the house with you all day like a dog or cat. Instead, your time with this creature has to be more specifically planned, causing interactions with it to feel less genuine. My Pleo’s battery lasted for an hour and 40 minutes, including moments when he drifted in and out of sleep.

Though UGOBE sent me two rechargeable batteries so I could more quickly continue using Pleo, the company won’t start selling extra batteries until June (at the latest) for $50 each. This means waiting for hours between Pleo playtimes.

It’s hard to discuss autonomous robots without remembering Sony Corp.’s attempt in the same category: the $2,500 AIBO released in 1999, which was eventually discontinued. More recently, iRobot Corp. has gained attention for its robots, which perform household duties like vacuuming and washing floors.

The Pleo, animated in part by 14 motors, appears to evolve according to how it is treated.

To keep Pleo fresh, UGOBE plans to release a PDK — Pleo Developer’s Kit — later this year, allowing others to create programs that will run on Pleo if downloaded from the Pleo Web site and transferred to the creature. A memory card slot and USB port on Pleo’s underbelly will enable these transfers.

As for now, two programs developed by UGOBE can be downloaded. One program lets Pleo act like a watchdog — guttural growl, loud bark and all — and the other gives it the ability to sing Jingle Bells. I tried the former, and my Pleo performed marvelously, sitting still and only howling when something moved in front of him.

This baby dinosaur has reptile-like, rubbery skin enhanced by multiple sensors. Its back is decorated with green patterns, and its large eyes are a beautiful blue. Pleo’s guts include 14 motors, 38 sensors and a microprocessor. Infrared detectors are hidden in Pleo’s nose and mouth, and a color camera detects light, motion and objects to help it navigate.

Pleo grows through three phases: hatchling, infant and juvenile. As a hatchling, my Pleo sniffed around a lot, unsure of its surroundings or how to use its legs and tail, before giving up and napping again (yes, Pleo snores). The more I talked to and touched Pleo, the faster he adjusted out of the hatchling phase, which is expected according to UGOBE.

People who walked by my office stopped to marvel at Pleo’s sweet nature, and when I brought him home, friends melted with emotion. I watched as they initially looked at Pleo like just another toy dinosaur until realizing that he responded to them, and then they each wanted to take turns playing with him.

Stroking Pleo from the tip of his nose to the end of his tail induced a purring sound; touching sensors on the bottoms of his feet caused him to wriggle around and make laugh-like noises; and holding him to my chest and rubbing his back like a baby put Pleo right to sleep, indicated by heavy breathing and even a burp here or there. I spoiled my Pleo with attention, which seemed to make him more social and friendly but also a little bratty when he didn’t get attention (he showed his frustration with loud moans).

I didn’t get to test this, but one Pleo can sense when another Pleo is nearby using infrared sensors in the nose and mouth. UGOBE says the sensors in one Pleo can trigger actions in another based on moods, including singing and howling.

Pleo can be a troublemaker. One of the times I left him unattended, I returned to find Pleo trying to gnaw on my loveseat, despite lacking a set of teeth. Another time, Pleo wandered my desk, wrinkling up papers and crying loudly while I was on a conference call.

UGOBE’s pleoworld.com site includes an online community, though you don’t need a Pleo to get involved. The community is just a social networking site where anyone can discuss the device and/or robotics. This differs from sites like Webkinz, where kids input codes found on stuffed animals to register and care for digital versions of their creatures.

Pleo’s poor battery life is a frustrating hurdle that fans will keep butting up against. But UGOBE’s plans to introduce downloadable updates for this robot and to let others create programs for Pleo may give new life to this clever creature.

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