I mostly play Vanguard right now and AFAIK Vanguard uses the Unreal 2.5 engine. When the expansion hits, they're supposedly moving to the Unreal 3.0 engine. Rainbow Six: Las Vegas (or whatever the newest Rainbow Six game) also uses Unreal Engine 2.0 or 3.0 and the x2900 is pretty much on par with the 8800gtx (according to anandtech). So basically, I'm going to wait until I see some more benchmarks with the x2900 on some dx10 games or games utilizing the unreal engine...