Latest Vista Update Helps Keep Your Copy Genuine
 

This update for Windows Vista detects exploits that may be present on a system. An exploit bypasses licensing and activation. This behavior allows for counterfeit copies of Windows Vista to run without ever having to be activated. Activation exploits make alterations to key Windows system files. These exploits affect both system stability and security.

When the update is installed, no functionality of your operating system will be affected. If no exploits are detected, the update silently exits. If exploits are detected, you will be provided a link to a Web site that describes how you can remove the exploits. When the exploits are removed, you may be asked to use a valid product key to activate your copy of Windows. If you do not want to remove the exploits, Windows may disable the exploits and then ask you to use a valid product key to activate Windows.

http://support.microsoft.com/kb/940510

good call on telling people... when i do builds for people i have to say just about the same thing... cept for XP.. SHHHHH