As Microsoft has released Service Pack 1 for Windows 7 & Windows Server 2008 R2 it is advised that you must install service pack to keep your system secure and updated. But there may be instances were you may need to stop automatically updating of service pack. Like organization or administrator might like to test the compatibility of service pack with their software.
You can block the service pack for automatically updating with Windows Service Pack Blocker Tool Kit. This toolkit can stop installing of service pack via windows update, but toolkit will not prevent the installation of the service pack from CD/DVD, or from the stand-alone download package. This toolkit is valid through 22/2/2012 after that Automatic Update will install the service pack.
The tool kit consists of three components: a Microsoft-signed executable, a script, and an ADM template. All of them set or clear a specific registry key that is used to detect and block the Service Pack download from WU. Companies can choose the one that works best with their computer management infrastructure.