Virtual PC 7 is a successor of Microsoft Virtual Server 2005 R2 SP1 and it is available as a download for Windows 7. Combined with Windows XP mode it will give administrators opportunity to enable legacy applications for their users without the risk of degrading or corrupting Windows 7 installation.
My personal recommendation is to install Microsoft Security Essentials into Windows XP mode so your “virtualized” OS and applications are safe from viruses and malicious software. If you have some other AV solution you are free to install it in XP mode virtualized OS.
Windows XP mode has been available to TechNet and MSDN subscriber for a month now, and now it is available to all Windows 7 users. Bare in mind, that your computer has to fulfill certain hardware and software requirements: