Install, reinstall, upgrade or uninstall Windows - a new Microsoft Windows webpage providing information for when you need to Install, Reinstall, Upgrade, or Uninstall Microsoft's Windows. (Thanks Chris)
INSTALL WINDOWS: If you're installing Windows for the first time on a new computer and you don't have any existing version of Windows to remove, upgrade, or replace. To install Windows and keep an earlier version of Windows on your computer, click on: Install Multi-boot
REINSTALL WINDOWS: If you have an existing installation of Windows that you want to reinstall.
UPGRADE WINDOWS: "How to . . ."
Windows XP -
Windows Vista -
Windows 7 -
UNINSTALL WINDOWS:
Uninstall Windows XP - You can't!