I haven't come across a Windows 7 compatibility issue yet with any of my games, and I'm also using the 64-bit version.
I just purchased a Radeon 5870 graphics card, and it came with DiRT 2, which is one of the first DirectX 11 games. I think it's awesome!
Also, ever play Unreal Tournament 3? It's a fun first-person-shooter; that's probably my favorite game right now (it uses DirectX 10).