I built a new rig about 2 months ago, it is all going pretty smoothly,
Im running a Q9450 @ 3.2ghz
4 gig ddr2
asus p5e deluxe
The system runs well. Crysis (the most demanding game i own) runs at about 35 fps average on 1680 res with all settings high. (it raises to about 45-50 in quiet areas and in extremely demanding areas can dip to 25fps)
The plan was always to buy the 4870 as a stopgap then either add a second 4870 when the price dips or sell it off and get a 4870x2, however i am now debating whether to keep what i have or upgrade
An upgrade may not make sense unless there is a BIG jump in performance. I don't see that here. Almost nothing runs Crysis at high fps. For other games, if you can average 60fps, then you don't need more to enjoy good gameplay.