If you are looking for a way to do massive Windows 7 migration, Microsoft has updated its own tool sets for this purpose, called the Windows Automated Installation Kit or WAIK. It has a lot of new features for both Windows 7 and Windows Server 2008 R2. This screencast shows how it works:

http://itexpertvoice.com/home/using-windows-aik-to-automate-windows-7-deployment/