Time Machine is for Macs (in fact, there's no Mac software included), and seems to do a pretty good job of it. You merely plug the drive into your computer, accept a license agreement, and you're off to the races with hassle-free incremental backups of your system. The drive is available in Single PC and Multi-PC models, with the former sporting 250GB of capacity, and the latter doing 500GB and adding in a vertical dock -- but to actually backup multiple PCs you'll have to move the drive around sneakernet style. ComputerShopper found the drive pretty slow, and while you can drag and drop files off of the drive, it doesn't actually allow you to toss specific files on and use the drive as way to move your projects around town. Still, it's simple, and the $200 starting price isn't criminal.
Read - ComputerShopper review
Read - Official Replica site