I just got a new computer with Windows 7, and while I can get a cheap 7 Ultimate license through my university (so XP Compatibility) I'd like to know which games are 7-compatible now. Is there a list of currently Win7-compatible games?
Just because a game doesn't have the Windows 7 tag on the catalogue entry doesn't mean it won't work. There are fewer than a dozen GOG releases that have compatibility issues on 7, and most of these can be fixed manually in the meantime. Refer to the GOGs not working on Windows 7
thread for the specifics (mentions of "Game UX" and the like are regarding Games Explorer integration, not the games themselves).
For most games the only problem you'll see is that Games Explorer entries don't work correctly (you can still launch the games just fine from the Start Menu and everywhere else, so this is no big deal).
EDIT: also worth noting is that GOG compatibility is the same on both the 32-bit and 64-bit flavours of Windows 7. If your system is capable of running 64-bit Windows 7 that's the one to go for for a variety of reasons; among other things the 64-bit versions of Office 2010, PhotoShop, etc. are noticeably faster when performing some tasks, and if you're stuck with a 32-bit OS you can't take advantage of this.