InFeXiOn:
What does the rest of your rig look like (CPU/RAM especially)? I have found that those components have as much impact on WoW performance as the GPU. With a 7600GT paired with an e6400 and 2GB DDR2 (all stock speeds) I was able to run with all eye candy at max up to 1280x1024 completely smooth (1600x1200 was a little jerky in the cities). Swapping the 7600GT for a stock x1900gt (rev1) allows me to run 1600x1200 totally smooth with all detail set to max.
My buddy used the same model x1900gt in his system (e6300/512MB--don't ask, I didn't build it) and he could only run 1024x768 completely smooth with medium quality settings. We bumped him up to 2GB RAM and overclocked his cpu to 2.33GHz and now he happily plays WoW at 1280x1024 (max resolution of his LCD).
I see that you already have the 8800GT coming and I figure you will probably be happy with it, but if you don't see a dramatic improvement you will have to evaluate the rest of your rig to see if something else is holding you back.