I will first tell you about my setup, I run vista64 pro, with 4gb ram, 250gb HD and quad core processors running approx 9.4ghz, the graphics card i am using is the Geforce 8800GT 512mb.
I use my computer for gaming, and autocad to it needed to be pretty fast, the 8800 is not the fastest card money can buy, but after extensive examination of the competition i decided to go for the cheaper model, and am not dissapointed at all, its very fast and handles everything i throw at it, runs all games very smoothly on extreme settings, if you are looking for a card that will keep you playing top of the range games for the next couple of years you cant go far wrong with this one, to boot it remains very very quiet in the computer. I have never had any overheating problems and its also suitable for overclocking should you need more speed.