Motherboard support?

Ok so i think it might be a dumb question but i wanted to double check before the order.

i have a asus m2n-sli32 deluxe dual 8800gt in it right now. i am planning a new build and before i do so, i plan to get a ati5870.

i am just making sure the motherboard supports ati, which pretty sure just not in xfire. sorry if i am right and this thread is a total waste but a quick answer would be great thank you.