I want to buy a Gforce 6800 gt or a radeon x850 pro. They are completely the same apart from the core clock (geforce 350mhz/radeon 500mhz), number of pixel pipelines (gf 16/rad 12) and price (gf 249/rad 222). Now, which one to get? And my computer is quite old with a processor of 2.7ghz from intel, would it be enough to run both? Should I also buy a new processor?