You should NOT attempt to delete the following folders :
C:\Windows\ServicePackFiles
C:\WINDOWS\DriverCache
....under ANY circumstances, they are essential for the normal operation of
XP when WFP (Windows File Protection) is enabled.
However, the following folder is needed if you ever need to uninstall the
previous Service Pack :
C:\WINDOWS\$NtServicePackUninstall$
....but if you are absolutely SURE you will never need to uninstall the last
Service Pack, removing this folder will not impact on the system in any
other way. One option would be to burn this folder to a cd-rom before
deleting it entirely, then if a situation arose where you needed to
roll-back the last Service Pack you would be able to do so after copying
the folder back to it's original location.
The following folder enables the uninstalling of any of the subsequent
individual "Window's Updates" and should NEVER be removed :
C:\Windows\$hf_mig$
....as you will no longer be able to uninstall any installed updates if it
is removed.
However, all of the above folders are capable of being compressed to
minimise the impact they have on the space they use on the drive. They
should also be "hidden" folders, so while Explorer is set to "Show hidden
files and Folders", right-click on the selected folder and choose
"Properties" then click on the "Advanced" button - if not already
checkmarked, select "Compress contents to save disk space" then press [ok]
to save and exist the dialogue.
==
Cheers, Tim Meddick, Peckham, London.