Few days back Microsoft has announced the public availability of Windows Vista SP2 and Windows Server 2008 SP2. Service Pack 2 would be available through Windows Update, but a blocking tool is available for organizations/individuals who would like to temporarily prevent installation of Service Pack updates through Windows Update. Once installed, the Blocker tool will prevent SP2 through Windows Update and it will be valid for 12 months following general availability.
This blocker toolkit contains three components. All of them function primarily to set or clear a specific registry key that is used to detect and block download of Service Packs from Windows Update.
This tool writes an entry into the registry to ensure that the SP2 is not delivered through Windows Update. The key used in registry is HKLMSoftwarePoliciesMicrosoftWindowsWindowsUpdate.
Important thing to note is that this toolkit will not prevent the installation of the service pack from CD/DVD, or from the stand-alone download package. This simply prevents the service pack from being delivered over Windows Update and is valid for 12 months from the general availability of SP2.