Virtual Machines is a technology that allows one physical computer to host multiple OS’s.  Microsoft has various flavors of VM software.  VMware is a SW company that focuses on providing VM solutions. Paul Young recently loaded his Windows Home Server OS on Media Center PC as a Virtual OS using VMware VMWare Workstation 6.5. You could also use Windows Virtual Server, but VMWare may have slightly lower overhead and better direct hardware and USB support. Virtual PC / Server have no USB support. 

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