Ahh ok -

Just FYI - changing resolution in WoW will barely if at all make a difference in FPS. I have gone as high as 3000x3000 resolution and still - my actual rendered area is the same.

Of course, my FPS goes to crap but not because of the resolution. It goes to crap because I am spanning across multiple video cards.

Didn't realize Vista removed horizontal span. Without that, I know of no real way to get it going short of multiple machines.

Eventually, you could use VMs but no VM that I know of does DX 9 yet.