New grahpics card & PSU

Do you have a price range? If you want the absolute best from 1680x1050 on GTA IV, even the strongest single-GPU card can get you trouble with a Q6600@2.4GHz. The combination of the TX650W and the HD 5770 isn't too bad, but the 5870 will pull you the best FPS on GTA IV. With that being said, going with an HD 5870 simply for one or two games might not be worth it. I'd go for that combo if you want okay FPS on GTA IV but still be able to run every other game, excluding Crysis, at the highest settings with 2x or 4x AA.

I'd look at the 4890 ($200) unless you're willing to shell out a bit more for a 5850 ($260 I believe). The Corsair TX650 is a good one and should last you quite awhile. It's really hard to give advice on mid-ranged cards atm since the new tech is just now inching it's way out the door. Future proofing for DX11 is nearly impossible without spending $3-400 right now. In my opinion, the most intelligent purchase for a mid-ranged GPU seems to be the older top-end 48xx series. I'm also reminded how long the top DX9 cards lasted after DX10 released...pretty sure I wasted a ton of money back then and didn't play a DX10 title for a good year afterward ><

Thanks for the replies all, appreciated. I'm actually going to build a completely new PC, so I was wondering where the appropriate section would be for posting a question about a whole new build?