I heard that the hd6850 and gtx 460 were on par with each other. I am now hearing that the hd6850 and hd6870 are the replacements for the 5770. Is the hd6850 as good as the gtx 460? If not I will get the gtx 460. (I do a lot of research) I also heard that Nvidia cards are better for lower end CPUs because of the Physx engine. Would it efect my FPS if I used a gtx 460?