2x 295 in quad vs 2x5870

hi,
I am building a new pc I have xfx295 which I got last week I am thinking of runing them in quad It would be hard to sell..... but maybe its possible if I can trade for an 5870 and get another 1 and crossfire em and its possible I can buy another 295 xfx.
I am looking for the fastest fps on i920 set up I searched for reviews but all put single 295 against it to compare. My current system q6600 3.2 oc 4gb 1066 and some crap hdd and 800 w psu and vista 32 bit.
Some or most games run 30 - 90 fps on 1920x1080. The new system will have ulitmate installed on it 64 bit.
suggestion thoughts let me know which set up is faster.