Just a small comment about framerate. WoW isnt a FPS, a frame rate of 15 is way enough as long as you arent doign massive PvP. Of course the graphics arent going to be at their best, but still you rarely have the time to pause and look around anyways! Personnaly, I think that graphics are for screenshots, gameplay is the most important thing.
Hopefully, the new mini rev that is around the corner should improve performance even more to put it at a respectable level.
I have the 1.42 with a gig of ram and it is defintely playable. I have a few of the settings turned down but it runs fine for the most part.
I just got WOW, running it on my mini 1.4 with 512 ram. I have everything turned down, and the res at 8x6, and it's fine for the most part. a bit slow in cities like Ironforge but otherwise it's great!