About the same size as an issue of TIME, and at its thickest point still thinner than a paperback, the MM20 is a waif in spite of its 10.4-in. XGA LCD screen. It's the first PC sold in the U.S. to sport Transmeta's new Efficeon chip, a 1GHz processor that can handle the essentials of a Windows XP environment without need for a fan to cool it down. Plus, there's a 20GB hard drive and 512 MB of RAM.

With its relatively small battery, the MM20 runs for two to three hours on a charge. When I tested it, I got roughly two hours at full performance; in "mobile" mode, with the processor slowed down and the screen backlight dimmed, you can stretch out battery life. (There's an optional high-capacity battery for $199 that can provide up to nine hours of juice.)

The system has 802.11g Wi-Fi networking built in, which means that if you have a newer Wi-Fi router you can share video and other bandwidth-hogging files without many glitches. If you have the older kind of router (802.11b), the MM20 still works, just at a narrower bandwidth.

One of the unique features of the MM20 is that it can function as an external USB 2.0 hard drive for your desktop computer. When shut down and docked, the notebook's hard drive can become the receptacle of your important work files, so that you have them when you're traveling. Assuming your company likes you enough to spend $1,500 for a second PC, you get the convenience of the ultra-light without having to rely on it when a larger, faster computer would be more pleasant.

The system is not without flaws. I wouldn't use it to edit home videos and I wish that there was a way to magically squeeze a larger hard drive in there. Also, I've seen longer battery life in chunkier notebooks with Intel's Centrino chipset. Still, for someone who, like me, needs to be comfortable when writing, the closer a notebook gets to weightless, the better.