I've been using Maxtor's new ultra-portable external hard drive for a few days now, the OneTouch III Mini Edition, a 100GB hard drive that easily fits in a jacket pocket and weighs about seven ounces.

What makes it different than other portable hard drives? Power, that's what. With a typical external USB drive, you need to plug in an AC adapter to get enough power to run the drive. This is inconvenient when you're on the road and there's not a power plug in sight.

What the OneTouch does to solve this problem is provide a special cable that has two USB plugs on it: One handles data, one draws extra power from the PC to spin up the drive. (If for some reason that doesn't give you enough juice, you can get an external power adapter too, but every machine I tested the OneTouch on could power it fully from the two USB plugs.)

Of course you also get the single button backup, integrated software, and a sleek and rugged case. The 100GB model is $200, a good price, though you can find cheaper external hard drives if you poke around. But in my mind, the Maxtor's features make it worth its slight premium price.