In tip 0156 and tip 0191, I first described a method to accomplish this.

Another way to accomplish this is to make use of the unattended switches available in a Service Packs UPDATE.EXE and a Hotfixes HOTFIX.EXE.

When you download a Service Pack, you can expand it to a distribution share, using ServicePackName.exe /x. The Service Pack UPDATE.EXE is in the \Update sub-folder and supports the following switches (SP4 and greater):

-f  Force applications to close at shutdown.                              -u  Unattended installation.                              -n  Do NOT create an uninstall folder.                              -z  Do NOT restart.                              -q  Quiet mode, no user interface.                              -o  Overwrite OEM files without prompting
When you download a hotfix, you can expand it using HotfixName.exe /x. It expand them to a a sub-folder that is the hotfix name, such as Qnnnnnn. HOTFIX.EXE is in the Qnnnnnn sub-folder and supports:
-f  Force applications to close at shutdown.                              -m  Unattended installation.                              -n  Do NOT create an uninstall folder.                              -z  Do NOT restart.                              -q  Quiet mode, no user interface.                              -y  Uninstall (only with -m or -q).                              -l  List installed Hotfixes.
I create a re-application script that my users (local administrators) can use to reapply the Service Pack and hotfixes:
                              \\ServerName\DistributionShare\NT4\SPn\update\update.exe -q -u -o -n -z                              \\ServerName\DistributionShare\NT4\SPn\Q123456\hotfix.exe -q -m -n -z                              \\ServerName\DistributionShare\NT4\SPn\Q234567\hotfix.exe -q -m -n -z                              \\ServerName\DistributionShare\NT4\SPn\Q387008\hotfix.exe -q -m -n -f
NOTE: The last hotfix forces the applications to close and the system to restart.

NOTE: If this was an original install, I would create uninstall folders for the Hotfixes, simply to document it.