Anytime Upgrade in Windows 7 no longer performs a full reinstallation of Windows. Components for the upgraded editions are instead pre-installed directly in the operating system; a notable result of this change is that the speed of the upgrade process has been significantly increased. Microsoft stated that an upgrade should take approximately 10 minutes.
The Anytime Upgrade feature in Windows 7 has been modified so that it doesn't require a full reinstall of the operating system. Instead, it installs upgraded components directly into the existing system, resulting in a faster upgrade process. Microsoft claims this upgrade should take approximately 10 minutes.