hi,
i have the same system with 2x295gtx and i7950 win7-64.
on this system the game is unplayable at normal/low settings for me.
On my second system Intel q6600 8800Ultra 4gig ddr2 win7-64 i can play on very high settings VD 5000m without lag and load stuttering.
i7 and 295 GTX very poor performance ~20fps [1680x1050, all settings middle, 1200vd], keeps crashing (now with blue screen).
q6600 and 8800ultra runs perfect without any lag at 1680x1050, all very High, 4500vd.