I'm at 1920x1200 everything High, full AF and 2xAA on a 7900GS currently and I think it doesn't drop that much. I'll double check when I'm home though.
This area has been a problem with me even after upgrading to my E6750 @ 3.4ghz and it's a problem even when nobody is at the FP. It is the most bizarre thing.
It's something coded in the game wrong, not my graphics card. It's this one spot in the game that cripples my system. I can go in a spot with 100 other players and not have this issue, but those 10-15 NPCs ruin my system.