Do you remember a time when Windows Vista SP1 was not available as a public download? In the pre-Release Candidate Stages of Vista SP1, Microsoft restricted the access to the service pack only to selected testers. In this context, a registry hack emerged, designed to permit the access, downloading and installing of Vista SP1 even outside of the limited testing pool. And as the Redmond company was delivering the beta versions of the service pack only to a limited number of testers, the registry hack was an alternative to grabbing the various development milestones of Vista SP1 straight from Microsoft.

On December 11th, Microsoft made available for download the standalone installers for Windows Vista SP1 RC1. But at the same time, the company debuted the Windows Vista Service Pack 1 RC Public Availability Program, allowing users to access the refresh via Windows Update. Now, from a RTM version of Vista, simply looking for SP1 on Windows Updates will not identify the service pack. This is why Microsoft has provided the 348 KB SP1RC_Public_Availability_WURelease.exe. If you have already deployed the first service pack for Vista, then you should make sure to uninstall it before proceeding with the deployment of SP1 RC1. The executable offered is nothing more than the hack made available in the past.

"On Vista RTM download the self extracting executable and extract its contents to a folder on your computer. Run the script on an elevated prompt. To run the script on elevated prompt, after you download the script, right click on the file and select 'Run as administrator' option. The script sets a registry key on your system. The registry key is required for WU server to recognize your machine as a valid target for Vista SP1. After running the script, Windows Update automatic updates would normally automatically update your machine each night for the next several days with the prerequisites and then offer the Service Pack. However if you would like to install SP1 quicker you can manually do the next few steps to speed up the process", Microsoft revealed.

Searching Windows Update will deliver the users with a few examples that need to be downloaded and installed. The process has to be repeated quite a few times, and the users will have to go through a few reboots. At a certain point, WU will offer in order Update for Windows (KB937287), Update for Windows (KB938371) and only then Windows Vista Service Pack 1 (KB936330). Sometimes, users will have to wait extensive periods of time before checking for new updates and actually receiving the necessary results from Microsoft.

"To reduce the number of reboots required to install Windows Vista Service Pack 1, the prerequisite packages will be released to Windows Vista customers through WU prior to the release of Windows Vista Service Pack 1. These prerequisite packages will be coupled with other updates that are applicable to Windows Vista RTM systems and require a reboot. Consequently, the systems that are getting updates through automatic updates will already have prerequisites installed at the time of the SP1 release and be directly offered SP1 through WU", Microsoft added.