System Update Readiness Tool (KB947821)
When SP1 came out some people experienced issues with installing it with problems like looping reboots. This tool that was released Tuesday checks to make sure that your copy of Vista is susceptible to such problems and fixes them if needed.
http://www.microsoft.com/downloads/details.aspx?FamilyID=d22af4e2-1aaf-4672-8951-4b7920f982e9&DisplayLang=en
Thanks to James Senior :) http://blogs.technet.com/james/
Ravi Nar
"Somebody give me the baton I wanna run!"