"It will require a 64-bit version of Windows 7 or 8 along with a DirectX 10 or 11 compatible video card"
I think this is a good move, I did the same for my game. It opens up a lot more memory addressing and cool GFX features. But my question is, have you also multi-threaded most part of the game like AIs' logic, etc? Gamer computers nowadays have lots of cores and I see so little games take advantage of this new processing power.