I had a devil of a time installing it, kept getting "access denied" and the install would abort and rollback to SP2. In the end I was successful. I had to: 1) uninstall Spybot (a malware protection utility that besides other things monitors changes to the registry) 2) uninstall Googleupdater 3) turn off my AVG Resident Shield (my antivirus sw). 4) I had to run the script from this link to reset registry permissions http://blog.malwareteks.com/correct-access-denied-error-while-installing-windows-xp-sp3-release-candidate-2/ Good luck Chuck