I'm not generally a Mac fanboy but damn if the Time Capsule isn't the most it-just-works backup solution I've ever used. I really want to find a similar setup for my Windows boxes.
While it's not "plug-and-play" like Time Capsule, Crashplan is pretty good. I've been using it for about a year now and so far its been working flawlessly for me. All my Windows boxes get backed up daily to my Synology NAS (note: this is a third party package, so your mileage may vary).