I think I've probably confused everyone. My PC came with Vista already installed. It was not an upgrade from XP.
The article I was reading was talking about the files that were left after the many updates that Windows XP did. It said that if you were satisfied and knew you weren't going to roll back before a particular update you could delete all of the old update files.
It explained how to do this in XP and since I also have another PC that does indeed run XP I was also to relate to the article. But this newer PC with Vista was not so easy to relate that article to. I searched but could not find where these old critical updates appeared.
The article was in the May 2008 issue of Smart Computing, Page 27 just in case you have access to it.
Sorry if I confused everyone.