(1) (virtual PC) Generically, a PC that runs in a virtualized environment hosting multiple operating systems, each with its own applications. See desktop virtualization.
(2) (Windows Virtual PC) Specifically, virtual machine software from Microsoft that enables multiple Windows and DOS operating systems to run simultaneously in the same machine. Formerly Microsoft Virtual PC, Windows Virtual PC became a free product in 2006. Virtual PC is Microsoft's desktop virtualization solution, whereas Virtual Server and Hyper-V are server-based products (see Microsoft Virtual Server and Hyper-V). Virtual PC was developed by Connectix, which Microsoft acquired in 2003. See Windows XP Mode and Virtual PC for Mac.