It aint the graphics card, its overkill for wow.

I assume yeh got yeh got one copy for each game? or yer symlinking it therefore have one config file for each game?

Whats the res set at?

got anything else running?

are the graphics card set to spanned mode?

try setting up 2 copies on one core 2 on another then yer main on a separate core.
that way XP and yer main gets its own core.