Windows 7 has fixed it sorta but sometimes it doesnt work right on my rig.

I monitor the 2 cards with GPU-Z watching their clock speed & temp,

W/ W7 Professional, the second card would not click up to full speed despite having 4 clients on it

But with innerspace forcing wow to use the correct GPU, the card would work perfectly and as hard as the first, therefore balanced load on both cards. (this is based on my observation of the temps of both cards.).