Microsoft has released Windows Vista Service Pack 1 (SP1) Release Candidate Preview to invited 15,000 Microsoft Connect technical specialist and testers. This RC version of SP1 apparently been falsely advertised in MSDN two weeks ago, but quickly been retracted. Microsoft intends to officially release Vista SP1 in first calendar quarter of 2008.

Windows Vista SP1 RC Preview release also include the standalone installer of all MUI language packs for all 36 supported locales, as the same with Windows Vista SP1 beta release. The build number of the Windows Vista SP1 RC Preview is 6001-17042-071107-1618, and was last compiled on 7th November 2007. Apparently, the build version of the Vista SP1 Release Candidate is the same with the Windows Vista SP1 beta v.658 released via Windows Update.

Installing Windows Vista SP1

However, although major and minor version number for Vista SP1 RC Preview and Vista SP1 Beta v.658 is the same, however, in Windows Update it’s still been labeled as Windows Vista Service Pack 1 Beta. Probably it’s the maintenance and build versions are different, but we can highly suspect that Vista SP1 beta v.658 is indeed the Vista SP1 RC Preview release. So download and install Vista SP1 RC Preview now on Windows Update.

You may need to apply the following registry hack:

@echo off
reg add HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\VistaSp1 /v Beta1 /t REG_SZ /d 37d55f36-65d6-4fe4-9dc7-892fcbe6222b /f
reg add HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\WindowsUpdate\VistaSP1 /v Beta1 /t REG_SZ /d 37d55f36-65d6-4fe4-9dc7-892fcbe6222b /f
echo Vista SP1 registry key has been set. Please check for updates in Windows Update.

Update: Windows Vista Service Pack 1 Release Candiate 1 Build 6001.17052 now released.