To tell you the truth, the 4850 is a better card than the 8800gts 640mb, no doubt about it, it's a big step ahead. BUT, the 8800gts 640mb is still a great mid-range card. So the question here is, what is the resolution you play
? IMO, save your money and wait for the next generation of cards and THEN change. I own 2x8800gt in SLI and i play everything Maxed out with some AA @ 1680x1050. So that is exactly what i am going to do, wait for the next gen. Hope that helped.