Microsoft includes SLI/Crossfire tests for WHQL Certification Process
 

the most important thing is that vendors will no longer be able to ship WHQL drivers for Windows XP and Windows Vista that don't correctly support dual graphics cards in that operating system - anyone trying to get SLI or CrossFire to work properly on Vista will know exactly what we're talking about here.

http://www.yougamers.com/news/2528_m..._whql_process/