I just built a new Win 7 unit this week and Risen works perfectly. The only problem I have is that sometimes I get a insert original disc error but I got that on my old XP computer too.
I went from Win XP Pro 32-bit to Windows 7 64-bit and have been surprisingly happy! Risen plays like a champ, no crashes or freezes! Video cards (pair x1950's) run a little warm, but that's another issue.