Windows Service Pack Blocker Toolkit
Here’s an update for those of you who have installed the Service Pack Blocker Tool for Windows XP or Windows Vista. This code temporarily prevents the installation of a service pack through Windows Update, typically for one year after general availability of the service pack. The expiration date for the Service Pack Blocker Tool for Windows Vista SP1 is April 28, 2009; for Windows XP SP3 the tool expires May 19, 2009.
For more information on the Service Pack Blocker Tool, please see the FAQ available through the Springboard Series on TechNet.