Microsoft has released an update for Windows Vista designed to detect activation exploits that bypass product activation and that interfere with usual Windows operation. This update is tagged as KB940510.
According to Microsoft "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/default.aspx/kb/940510
According to Microsoft "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/default.aspx/kb/940510