|Note: The following assumes that you have, or have access to the original Vista 32-bit .iso or can otherwise utilize the file install.wim contained within the .iso.|
1. Place the original Vista .iso on your hard drive.
2. Extract install.wim from the iso.
3. Extract all c:\windows\system32\wu*.* files from install.wim [I used the latest 7-zip beta].
4. Place all extracted wu*.* files in their own folder, e.g., C:\wu for later use.
5. Run Start, All Programs, Accessories. Right click on Command Prompt and click on Run as administrator.
6. Navigate to your System32 directory.
7. In order to replace current wu*.* files in the System32 directory, you'll need to first take ownership of each of them as follows:
Run: takeown /f "path and file name" [note: I ran this command for each of the wu*.* files, one at a time]
Run: cacls "path and file name" /G <your username>:F
8. Replace all wu*.* files using those from c:\wu
9. Register each of the original wu*.dlls in System32 - for example (regsvr32 wuapi.dll)
11. Place Windows Update in manual mode as a test and run it.
Thank you. :)