VMCX file stores data needed to run virtual environment on the base system. Virtualization allows users to run multiple system environmnets on single machine without the need of reinstalling operating system. Virtualization solution, beside VMCX files, uses VMC virtual machine files and VHD virtual disks.

VMCX files are used by Windows Virtual PC application available for Windows 7. The applications supports virtualization of Windows operating systems: XP (Professional + SP3), Vista (Business and higher), and Windows 7 (Professional and higher).