Seagate's objective in designing its Replica backup kit was to make a replica of Time Machine, but for Windows PCs. It works exactly as promised, and in similar fashion to Apple's no-brainer backup system.
From the blurb:
Unlike most backup utilities, the new Seagate® Replica™ backup appliance is a complete PC backup system, which automatically and continuously stores up-to-date copies of everything on a PC, including installed applications, operating system, e-mail, pictures, music, movies, Internet bookmarks and settings. Available in two configurations, the Seagate Replica solution delivers seamless backup for either a single PC or multiple PCs in a household.
Plugged in, its setup process was numbingly simple: agree to the TOS and you're about done. It then records a complete backup of your system and begins keeping track of changes you make. By cleverly journaling and organizing each sequential backup, the archive is unlikely to get substantially larger than the system it's attached to. As a result, you can dip into your machine's history, recover files, and restore the system in the event of disaster. It comes with a special boot CD to help in the event of the latter.
The drive itself is a pretty 2.5" model designed to stand upright on a dock, itself included with the premium edition. The supplied USB cable has an extra plug, useful should your computer not supply enough current through a single port.
After a few hours of use, I forgot it was there, which is the entire point. A "multi-PC" edition of the Replica kit, including the dock, will be offered for $200. A single-PC version will be $130.
Product Page [Seagate]