When I upgrade to Windows 7, I would like to keep the Windows installation and my data separate. Possibly install Windows itself on a small SSD for the performance gain.
I know I can tell Windows that I've relocated my user data, but some applications like to assume that everything is on C:. To fix this, can I just create a symlink on my Windows drive that points to the separate drive? I've done it with Steam's SteamApps directory so I can store games on an external hard drive, but I'm not sure what problems this could cause by symlinking something vital to Windows.
Plus, what about future upgrades? Will the Windows installation be able to traverse symlinks and properly upgrade everything?
(I would try this myself, but I don't have a MSDN/TechNet subscription, so it looks like I'll have to wait.)