HD7970 and nice water for the Q9550 (which you may move to your new build) A second HD7970 when you build your new rig should work well for you.
Pay close attention to benchies when Haswell rolls out. AMD seems to be working with game devs to optimize Piledriver performance.
(or, not, if you wish to stick with Intel !)
Edit: I mean ... move the water ... not the Q9550