Dude, dont waste your money on dual 6800 GT's. Just get a single 6800 Ultra. The Ultra alone will work better. I suggest a Abit AN8. Change your sig too man..
Is that system even possible? I dont see how 4 cpu will add up to 26 ghz when the fastest i have seen an amd is like 4ghz that would mean that each one of your processors is running at 6ghz=Fried