KillerGamer :
I would go with the Nvidia cards as I would prefer PhysX to the ypcoming Mantle. AMD cards perform better in many games but Nvidia cards have better details in textures due to PhysX. Compare Mantle and PhysX and see what you feel suits your requirements as this decision is largely based on personal opinions.
ok, firstly, I'm not one of those people who goes round the internet flaming. But. This is almost 100% erroneous. Physx is a tech dealing with modelling in detail objects that are in motion and the physics of said objects - a quick youtube search for the borderlands 2 physx demo should show you what i mean. It doesn't have anything to do with texture rendering it detail. Mantle, on the other hand, is an api that allows developers to code at a level closer to the base hardware, offering up performance increases in terms of framerates. Again nothing to do with detail of textures. While some games are optimised for each manufacturer, either amd or nvidia, there's little tle to no difference between the two in terms of textures. I believe they use different methods of antialiasing, and i believe, though do your research on this one, because I'm not sure anymore, that amd's method is faster, but dirtier than nvidias. As far as the original question OP, we may well see more optimisation for amd cards, due to the ability of mantle to code closer to the metal as it were, but only time will tell on that, its not something anyone could say for certain now. My advice would be to check which games you currently play or want to play for physx use. If they use it, you'll get a much better experience graphically ON THOSE GAMES. If you have no need for physx, then its much of a muchness and id suggest going for whatever you can get more bang for your buck for. Personally I'm considering AMD for my next upgrade for exactly the same reason, though i might wait till the gtx 8xx series comes out to make a decision. I hope that's cleared the water anyway.