A simple Google search for "Time Machine for Windows" results in a flurry of different little apps. But instead of relying on forum anecdotes and advertisements, I call on the much wiser Super User beta community for some depth on this one.
Having Time Machine running on Leopard is like a warm, fuzzy blanket of comfort that I never got with RAID, rsync, or SyncToy on Windows. I'm not asking the community what the "best" backup software for Windows is, but instead:
Is there any true Time Machine clone for Windows, one that includes as many of the following as possible:
Completely transparent, "set-it-and-forget-it" backup
Incremental backups (changes only) for every hour for a day, every day for a month, and every week until the backup disk is full
Ability to rebuild from this backup disk in case of main drive meltdown (the backup doesn't have to be bootable; neither are Time Machine disks)
Extremely easy to use UI (target user == wife). Bonus points for a beautiful UI