I think tht 6600Gt draws huge dollops of power but 865GBF shud handle it without any problems...also is ur P4 2.4 a 'c' version?? i mean is it 800fsb version or the 533 fsb version? If its 2.4C,get a 512 mb DDR400(better get 512x2,and setup dual channel memory)..then it shud perform like a breeze!!