If you are interested to test drive the latest version of Microsoft System Center Virtual Machine Manager 2007 you can download the virtual hard disk to use with Virtual PC or Virtual Server .
Overview
System Center Virtual Machine Manager provides centralized administration of virtual machine infrastructure and enables increased physical server utilization and rapid provisioning of new virtual machines by the administrator and authorized end users.
Download location (registration required): http://www.microsoft.com/downloads/details.aspx?familyid=d4e8bc52-3c3b-4bae-b937-987da892fad7&displaylang=en&tm