<i>This answer comes courtesy of virtualization expert Eric Siebert:</i>
That may have been true to some degree in the past, but since Microsoft recently instituted its <a href=”http://support.microsoft.com/kb/956893/en-us”>Server Virtualization Validation Program (SVVP)</a> program, it now officially supports running its products on non-Microsoft virtualization software like VMware.
The version of VMware that was validated was ESX 3.5 Update 2, so make sure that you are at least running that version if you try and obtain support on a Microsoft product. If you reference Microsoft article <a href=”http://support.microsoft.com/kb/957006/”>#957006 </a>, you will find a listing of all the Microsoft software that is included in the program. For more information on this new support program, read this recent <a href=”http://itknowledgeexchange.techtarget.com/virtualization-pro/vmware-achieves-microsoft-svvp-validation-new-reason-to-upgrade-to-esx-35-update-2/”">SearchVMware.com blog post</a>.