Make Windows Vista SP1 Permanent and Save Some Space
After you install SP1 in Vista and you’re happy that this service pack will work out well, you may want to delete the uninstall directories that are taking up a lot of space on your hard disk.
Simply run the command vsp1cln.exe.
This will allow you to easily remove the SP1 uninstall files. You mileage may vary depending on your Vista version.