Windows Vista Service Pack 1 Release Candidate 1 (Vista SP1 RC1) can now be downloaded and installed via Windows Update. The previous two hacks to install SP1 beta and SP1 RC Preview no longer works, and must be removed for the official Windows Vista SP1 RC to be shown up and available to install in Windows Update. It’s also recommended (MSDN WU upgrade instruction required to uninstall KB936330 (SP1), but user experiences confirmed that it’s possible to upgrade install) to uninstall “Service Pack for Windows (KB936330)” in “View installed updates.”

To trick to download and install Windows Vista SP1 RC1 (v.668) via Windows Update is to download the following batch command script, which taken care of everything – remove old registry keys and add in new registry key to Windows Update to target your machine as a valid Vista SP1 RC testing computer.

Download SP1RC_WUHack.cmd (no longer available).

Note: Microsoft has made available Windows Vista Service Pack 1 RC Public Availability Program which also applied the registry hack to get Vista SP1 RC installed.

Right click on the SP1RC_WUHack.cmd and then select “Run as Administrator” and confirm User Account Control prompt to merge the registry values and keys to the system registry. Then go to Windows Update and check for updates. The hack to download Vista SP1 RC from WU works on English version of Vista, and it comes witall Windows Vista languague MUIs. Thus users should be able to install Windows Vista SP1 RC1 on any editions of Windows Vista regardless of language locale. Else wait till official release of SP1 RC next week for standalone installer package, or follow the trick to force service pack for non-English Vista to show up in Windows Update.

Visit the guide to install online Vista SP1 RC1 via Windows Update.

All users, especially those never install Windows Vista SP1 Beta or RC1 Preview via Windows Update, will likely have to install 3 important prerequisites updates/hotfixes before Windows Vista Service Pack 1 is offered, as they’ve been updated. The 3 updates is Update for Windows Vista (KB935509) – v1.008, Update for Windows Vista (KB938371) – v1.028, and Update for Windows vista (KB937287) – Build 6001.17052 (x86 or x64). After restarting computer (important step, although system doesn’t prompt you to reboot), check for updates again in WU or Microsoft Update (MU), and you will see 1 important update available with size from 51.0 MB to 539.2 MB, which is Windows Vista Service Pack 1 Release Candidate 1 – Build 6001.17052 (x86 or x64).

Windows Vista SP1 RC1 Important Update

Windows Vista Service Pack 1 RC is near stable and near perfect release of SP1 test code before final release of SP1 in the first quarter of 2008. However, although it’s more stable than most previous version of betas, care should be taken before installing it, especially on production system as it may still causes system errors. This release also expire on June 30th 2008, but by that time everybody should be upgraded to final release of SP1 for Vista.

P/S: You can also copy and paste below code to text editor (Notepad) and save it with a filename with .cmd or .bat extension, and then run it with administrator privileges.

@echo off

reg delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\VistaSp1 /f > NUL 2>&1
reg delete HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\WindowsUpdate\VistaSP1 /f > NUL 2>&1
reg add HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\VistaSp1 /v Beta1 /t REG_SZ /d 536ee5c2-e79d-420d-a589-c8ab115f35c3 /f

IF NOT %errorlevel% == 0 ( goto ERROR)

echo ===========================================================
echo  Windows Vista SP1 registry key has been set successfully. 
echo  Please check for updates in Windows Update.
echo ===========================================================
goto END

echo ===========================================================
echo  FAILED to set Windows Vista SP1 registry keys.
echo  Please run this script by right clicking and selecting
echo  "Run as Administrator".
echo ===========================================================
goto END


Update: Windows Vista SP1 RC Refresh (v.774)