I little while ago some member of the Hyper-V test team released a new tool on code.msdn.microsoft.com.  It is the Virtual Machine Migration Test Wizard:

http://code.msdn.microsoft.com/VMMTestWizard

In Windows Server 2008 R2 we introduced a new “Processor Compatibility” feature (as discussed here).  The primary purpose of this new tool is to allow you to determine if you need to enable this feature in your environment to be able to move virtual machines.

You can also use this tool to determine how physical computers should be grouped – if you want to avoid turning this feature on.

There is also a video available from the author of this Tool – Dinesh – where he talks about how it works and demonstrates it running here.

Cheers,
Ben