Looking over at HardOCP seems like the drivers for Crossfire don't hold a flame to the Nvidia drivers. When SLI'ed 460's are close to Crossfire'd 5870's something is wrong.
I am not saying that I hate AMD, hell I have a 5870 but I can tell you that I will be going Nvidia. I loved my 260 and it never gave me problems. With my Shuttle build i'm going to use a 450. Hopefully that will be enough to push the pixels on a 28in Hanns-G.
I want to see what will come in the next few weeks.
Still going to go Nvidia though.