http://www.microsoft.com/windows/virtualpc/default.mspx
Virtual PC Is Now Free!
Whether Microsoft virtualization technology is an important component of your existing infrastructure or you're just a Virtual PC enthusiast, you can now download Virtual PC 2004 Service Pack 1 absolutely free. Microsoft is also offering the free download of Virtual PC 2007, with support for Windows Vista in 2007.
http://www.vmware.com/news/releases/server.html
VMware Delivers Free VMware Server
