Virtualization

Virtualization, simply put, is a method whereby more than one virtual computer shares the resources of a single physical system. It is a software environment that acts like a physical computer, executing programs as if it were one. A single physical computer thus can simultaneously act like one or more virtual computers.

Virtualization has several benefits:

• It allows you to run more than one computer on your physical computer, as we'll see a little later in this tutorial.
• It provides a layer of protection between the system that you do your work on and the underlying computer system that manages the physical resources of your computer.
• It allows you to use a logical method of using the resources of your computer.

Virtual hard disks (VHDs) are part and parcel of virtualization. A VHD is a single computer file that represents the entire contents of a hard disk. As such, while the underlying (physical) computer thinks of it as a single file, the virtual operating system thinks of the VHD as an entire hard disk, containing thousands of files.

Virtualization works best when you are using, or contemplating using, more than one system to perform specific tasks. As such, it is mostly a business-oriented approach to computing, allowing you to move several computers' worth of "system" onto a single set of hardware.

If you are a home user, we generally can't recommend virtualization as anything other than a special-interest topic, something that you probably won't get much out of. If you are a business user, even someone with a small home office, however, virtualization is something you might want to start thinking about.

Virtualization and VHDs are not new to Windows, having been introduced by Microsoft in 2005 as Microsoft Virtual Server. However, until Windows 7, virtualization has not been available out of the box with Microsoft's desktop operating systems, having previously been aimed at users of their server software. In addition, the availability of the new Windows XP Mode virtual 32-bit system (which we discuss below) is completely new to the Windows world as a product offering. If you are concerned about the stability of your Windows XP-specific applications while running under Windows 7, the section on Windows XP Mode, below, is just for you.