Other than standalone installation setup package of Windows Vista SP1 RC, Microsoft has also released Windows Vista Service Pack 1 RC Public Availability Program which makes available SP1 RC through Windows Update. The method is same with original registry hack leaked from Connect, Technet and MSDN. Although the registry key added is different, but the effect is same, indicate to Windows Update mechanism that you interested to install SP1 RC code in Windows Vista.

Users must uninstall any previous versions of Windows Vista SP1 before installing Windows Vista SP1 RC, and wait one hour after uninstallation to begin installation of SP1 via Windows Update as the installer service needs to clean up and complete the uninstall prior to installing the RC. Failing to do this can result in installation errors when installing the RC version.

As usual, a few prerequisite updates consist of two updates which service specific Windows components prior to the installation of the service pack and a third update which services the installation software built into Windows Vista will be required to be installed prior to SP1. This requirement is specific to RC build, while final SP1 setup will be these hotfixes rolled up during regular monthly updates. The following are the prerequisite updates.

  • KB935509 This updates is only required on Windows Vista Enterprise and Windows Vista Ultimate editions (which have Bitlocker capabilities). This update is required prior to installing KB938371, the second prerequisite update and is required to prevent potential loss of data on Bitlocker encrypted systems during updating.
  • KB938371 This update consists of fixes for several components (including the TrustedInstaller), increases the success rate for installing the service pack and enables the service pack to be uninstalled successfully.
  • KB937287 This is an update to the “Servicing Stack” or the Windows Vista component installer technologies built into Windows Vista. This update enables the built-in installer to properly and successfully install the service pack.

Windows Vista SP1 RC will be downloaded and installed via Automatic Update if you leave it as it’s after apply the new registry key. For those who impatient, open Windows Update and check for updates manually.

Download Windows Vista Service Pack 1 RC Public Availability Program via Microsoft Download Center – SP1RC_Public_Availability_WURelease.exe (no longer available). Once downloaded, unpack and run the SP1cppRK.cmd script.

Update: Windows Vista SP1 test version has been updated to Windows Vista SP1 RC Refresh (v.774) build 17128.