A virtual machine doesn't emulate Windows. A virtual machine manager or environment emulates the hardware that an operating system runs on and is in control of. A virtual machine can be of almost any operating system, Windows XP, Windows 7, Windows 8, Linux, etc. The operating system that has been virtualized thinks it's running on a motherboard, but in reality it is being fooled by the virtual environment. It is really running on top of, or inside of, another operating system, called the Host operating system.