As we all
know, Microsoft has been hard at work on the first Service Pack for Vista, but it seems some fixes can’t wait. Microsoft in article number 945149 offers a supported hotfix that addresses performance issue in certain multi-GPU configurations for Vista users. The only problem is that the users have to complete a form and request access to the fix from Microsoft technical support.
The bottom line is if you are running Vista in a multi–GPU configuration you might get better performance with this patch, but even Microsoft suggested that more testing might be necessary, so if you can wait for Service Pack 1, then you might be better off. Still, you have to jump through the hoops of requesting the hotfix and trying it; but it might improve your performance now, and depending on your situation, that might be what counts.
Get more information on the hot fix and requesting access to it here