I don't want to argue (for real.) Rather, I'm interested in sorting your issue. I aplogize. I think I get a little too defensive of Windows and ATI because I think they're both fantastic. I have yet to see an issue caused by them (MS, ATI, NVIDIA or Matrox) of this type of nature.
Is your card a PCI-E or AGP?
And is there any reason why you aren't connecting by DVI or HDMI cable?