Windows 7 XP Mode
Windows XP Mode is a downloadable add-on for Windows 7 Professional, Ultimate, and Enterprise. It has two parts: the virtualization software itself, and a disk image containing a pre-installed, activated, licensed copy of Windows XP Professional with Service Pack 3 preinstalled, complete with Internet Explorer 6.
Although you wouldn’t know it from the download page, this is available for any version of Windows 7 aside from Starter. You wouldn’t know it, because selecting a version of Windows other than those previously listed removes the option to download Virtual PC. It shouldn’t, though; it should only remove the option to download the Windows XP Mode image.
The new version requires hardware virtualization support—Intel’s VT or AMD’s AMD-V. Microsoft’s current server virtualization platform, Hyper-V, has the same requirement, but for Virtual PC this is a new demand. For virtualizing 32-bit guest OSes, far and away the most common usage scenario, the benefits of hardware virtualization are something between small and non-existent; though hardware virtualization is potentially a little faster, the difference in practice isn’t perceptible.