under superpi 32m....4x512MB 2T vs 2x512MB 1T I only lost about 40s, and Aquamark I only lost 1 FPS, only Sandra and Everest did I see a slightly bigger gap so it all depends what you want to do with you rig, if benching is all you do with it then I would stick with 2x512MB, but for everyday usage, graphic editing, and gaming...4x512MB rules!!

Major....very nice clock you got there with 4x512MB!! for higher clock...test the sticks individually first and put them in the slots as I suggested, then bump up your Tras to 7, Twr to 3, trtw to 4, idle cycle counter you can leave it at 16 clks, and for even more stability drop your read write bypass to 8x and bypass max to 4x. try utt 300 and see what happen