if you want my honest opinion i would tell you to save your money and just get sumthing not so high end right now, because your video card would be bottlenecking like a bitch, you wouldnt even "feel" the full effect of the card....id save an ass load of money and go with sumthing like the fx5700 or the fx5950
that would be an excelent upgrade for your current rig....if you want to spend the money though...as in like to have the card for a future rig...i'd go with the 6800 ultra or 6800 gt