Graphic Card Advice  

will budget become your concern? if not, buy HD 5970. You get the fastest GPU nowadays. If yes, try to buy HD 5870. That will be enough. Trust me. It is still worthed.

Btw, I think HD 6000 series will be coming at the end of this year. So, better for you to buy HD 5870 or 5850 for now. Or don't buy Graphic Card and wait for HD 6000.

Hi, if you had a Quad Core Intel processing chip and 4 Gigs of RAM, your configuration is pretty enough for any game released till date and for coming 2 or 3 years(atleast). I had used Nvidia Geforec and ATi Radeon graphics processors and had found some games arent happy with Nvidia controller. But ATi Radeon worked comparitively good and didnt made any problems than some exceptional cases.

But according to me, in your situation presently there is no need of any high power graphics accelerators since your machine is already powerful. Try to buy a machine which comes with onboard graphics accelerator for now. That will give you very nice graphics experience together with the power of your machine. Later, when games demand more and more power after 2 or 3 years you can move for a much better graphics accelerator. I think by that time the present day prices will fall into half or even lower than that. So you can buy a more powerful card by that time for the price of a card which you are now willing to pay.