Quote Originally Posted by Vmpwraith',index.php?page=Thread&postID=199836#pos t199836]2 GPUS in Vista may also cause a problem/Bug. Check out the sticky to the fix.

[url='http://www.dual-boxing.com/forums/index.php?page=Thread&threadID=21517
Possible fix for some of you with Vista and poor Graphic Card preformance low Fps[/url]

http://support.microsoft.com/kb/936710
" When a DirectX 10 application runs on a Windows Vista-based computer that has multiple graphics cards, the computer does not use the secondary graphics card"

  1. You have a Windows Vista-based computer.
  2. The computer uses two or more DirectX-compatible graphics processing units (GPUs) in a linked configuration.
  3. You are using a DirectX 10 application and driver.
In this scenario, the computer's graphics performance indicates that only a single GPU is being used.
CAUSE
This problem occurs because the operating system does not forward driver-render requests to the secondary GPU.

This may also be a problem. Anyway you can check it out. This problem will effect more than just running wow.
Later in this article the solution is given and reported to be corrected in Service Pack 1.