Hello Bruce Fullerton,
Welcome to the Forums!
Not to speak for Saladyn, but I think he is trying to advise you that should the need
arise to ever uninstall SP1 you will not be able to do so if you execute this command.
You may want to look at this Tutorial at the link below.
SP1 Disk Cleanup Tool | Quote: | Saladyn |  | |
| You can delete it. An if you want delete all needlessly file after install SP pres win+R and write Vsp1cln.exe . After this SP1 in vista stay forever in your system  | |
| | |
Later
Ted