But I'd try again with the full download of SP2 32 bit and this article. I can't be sure this will help because folk often run registry cleaners or have other system damage.

http://www.microsoft.com/en-us/download/details.aspx?id=16468

As to Sp2 install issues there must a few hundred causes and I don't see enough story to tell which one it is. Here's one of those stories.

http://answers.microsoft.com/en-us/windows/forum/windows_vista-windows_update/vista-service-pack-2-32bit-wont-install-kb948465/3eeb8d59-bcd3-449a-be0b-18a6c0b92891

Bob