If one installs Service Pack 1 (as opposed to installing a version of vista that included service pack one), copies of all the updated files are retained so that Servce Pack 1 can be uninstalled. Once you are satisfied that you won't need to remove service pack one, there is a utility that can remove thse obsolete files. Just find and run c:\Windows\System32\vsp1cln.exe. Note that the .exe extention is hidden by default in Windows Explorer.

And so I Just booted into XP for the first time in about 2 months in order to take a better look at Office 2007. As soon as I've logged in, the Sun Java updater alerts me that a new version of Java is available and asks me whether I'd like to claim my free copy of Open Office.