On January 9th, Microsoft released another version of it’s Vista SP1 code, this one called “Windows Vista SP1 RC Refresh”, to 15,000 testers. Microsoft was quick to note that this version would not be available to the public. Well, on January 11th, Microsoft released the same code to the public.

Like the other service packs, this one is primarily available through Windows Update, by changing a setting in your registry. You can download the small CMD file (and instructions) that will do this for you from this page. Here’s the code that gets run:

@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 c1ff1d2f-c61e-4f27-b68c-722061c201a5 /f
IF NOT %errorlevel% == 0 ( goto ERROR)

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

:ERROR
@echo.
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 ===========================================================
@echo.
goto END

:END
pause

As with other Vista SP1 betas, you’ll need to first uninstall any previous beta or RC SP1 code, and if you haven’t installed one before, there’s likely a few prerequisite updates you’ll need first. The instructions that come in the download let you know all the steps involved, but in a nutshell, double-click the CMD file, then keep visiting Windows Update until everything is installed.