You linked to a game that the 2GB ATi cards couldn't even play at 57X12.
My own needs are different than Kyle's. I'm gaming at 57X10, up to 4X AA because I only play first person shooters and I'm looking for smoothest gameplay. (not to get tiny increases in IQ at the expense of fps)
In any case, NVIDIA wins the multimonitor race hands down because:
1. They can do it in 3d.
2. NVIDIA OEMs offer gamers products at 1.5, 2, 2.5, and 3GB VRAM and ATi only has a couple 2GB products.