24% of steam users are already running Windows 7. XP is going the way of the dodo. can't be soon enough
Of course it will eventually, and in time 7 will "go the way of the dodo", but XP is still the best performing and most compatible Windows OS out. Cutting off half your market is kind of daft though, especially for an indie game. As Crysis proved you can emulate DX10 effects in DX9 and get a performance boost.