Do not perform the script to update WSUS in your production WSUS. It will point WSUS to the Beta update location and basically remove your production environment. Microsoft recommends running the script on a test server specifically for updating beta software. You cannot perform production WSUS and beta WSUS on the same server. At least this is my understanding of the document listed with WSUS SP1 web site. To return the WSUS back to the normal production update location, you have to remove and reinstall WSUS. Not good.
The best option is to:
1. Create an OU in Active Directory that is outside the scope of the WSUS Group Policy Object.
2. Move the computer with Vista into this OU.
3. At the computer, run GPUPDATE.
4. This will remove the WSUS from this computer.
5. Vista will now look automatically to the Microsoft Beta update site and download updates.
Windows Auto update problem Error 8007000D - TechNet Forums
Hope this works for you.
Please post back if you have any more problems or questions.