Hmm might have had AA enabled both places on my Win7 box. I don't have it installed, but as far as i remember orgrimar was my main issue at ultra and i did spend a lot of my time in that area at that time. Nvidia is a lot better at WoW than ATI according to some extensive testing by toms hardware a few months back:
http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793.html
But as promised, i just tested it on my iMac, and everything at Ultra in a small uncrowded town near silithus gave me 80fps looking around and in the area of 100 looking out over the horizon . Orgrimar outside the auction house fluctuated between 30-50 depending of how many tards showing off dragons

Durotar was a solid 100fps.
I'm quite impressed!
Though, something must be bugged with Liquid detail, Sunshafts, Particle Density and Texture Filtering and multisampling 1-8 i got zero change in performance by altering those. Turning Shadow Quality from Ultra to low doubled the framerates in orgrimar from 29 to 59 at the same spot changing back and forth.
it looked stunningly beautifu! the iMac is definitely capable of some serious WoW gaming.