What about an Nvidia 580 with 3GB Ram?
I would like to have Cuda for video conversion and Physx wouldn't hurt either. Plus 3GB Ram for maxd out AA and AF?
I would think you'd want to use Quick Sync, enabled by Virtu, if you are interested in hardware acceleration. You could get a 3GB GTX 580, however there isn't a huge performance increase over a 1.5GB GTX 580 (at least at 1920x1080 resolution, click me). There will probably be a slightly higher difference at your resolution. Keep in mind that Crossfired HD 6950s kick a single GTX 580's butt (click me). Obviously, PhysX enables incredible effects that AMD is unable to duplicate, so you'll just have to decide for yourself which card(s) would be better for you. I doubt you will be disappointed in either choice.