Btw,it seems you were comparing 4X AA and 16X AF GF100 results,with HD5970 results when running at 8XAA settings(look at them carefully),so they weren't running the same workloads.
Anyhow,here's my results at 1920*1200 with 4x AA and 16X AF,all other settings at ultra high just like Guru 3D,but running the latest 10.2 driver set:
My minimum FPS value is 75 FPS,and this is of course with one HD5970 card essentially disabled for this test.