If you haven't tried FolderShare yet, it's part of the Windows Live Service, take a look and see what it can do for you.
Keep important files at your fingertips - anywhere. All file changes are automatically synchronized between linked computers, so you are always accessing the latest documents, photos, and files.
I have two work laptops, a desktop at home and unsurprisingly many virtual machines. I also have a well used/planned back-up regime, which uses a specific folder I always create on each machine, so backing up is easy to either DVD or external devices. This has worked well for me, especially as I often re-build one or both laptops, for instance as I've been beta testing Vista one of laptops has been re-built almost weekly!
The only data I sometimes forget about is My Favorites. I now use FolderShare to make a copy of this data available to my other machines, I have two sub folders one that stores my "Work" favorites and the other my "personal" ones, theses are synchronized using FolderShare between the three workstations (it works on Vista as well as XP).
The other feature I really like is the "Access my Files" feature which gives access to all drives on each machine that FolderShare is running on. I often use this to browse to remote hard disks or even USB drives attached to the remote machines, this is the default behavior which allows access to all data, not just the synchronized folders. UPNP is utilized so I can even get access to my home machine whilst connected to the Internet.