See this KB for MS's stance on non-Microsoft virtualization:
It states that "Except as described in this article, Microsoft does not test or support Microsoft software running together with non-Microsoft hardware virtualization software. For Microsoft customers who do not have a Premier-level support agreement, Microsoft will require that the issue to be reproduced independently from the non-Microsoft hardware virtualization software. Where the issue is confirmed to be unrelated to the non-Microsoft hardware virtualization software, Microsoft will support its software in a manner that is consistent with support provided when that software is not running together with non-Microsoft hardware virtualization software.
For Microsoft Premier-level support customers running non-Microsoft hardware virtualization software from vendors with which Microsoft does not have an established support relationship that covers virtualization solutions, Microsoft will use commercially reasonable efforts to investigate potential issues with Microsoft software running together with non-Microsoft hardware virtualization software. As part of that investigation, Microsoft may require the issue to be reproduced independently from the non-Microsoft hardware virtualization software. Where issues are confirmed to be unrelated to the non-Microsoft hardware virtualization software, Microsoft will support its software in a manner that is consistent with support provided when that software is not running together with non-Microsoft hardware virtualization software."
So if you have a Premier agreement, they will use best effort to support you and may require you to reproduce the issue in a non-VMware environment.
