Q: If Microsoft releases a replacement
for a buggy security update,
do we need to uninstall the earlier
update before installing the replacement?
A: It shouldn't be necessary to uninstall the
buggy update. Windows Server Update Services
(WSUS) will either reinstall the new version
or prompt you to approve the update for
installation, depending on your configuration.
In some cases, you must rerun discovery for
Windows to realize that a new version of the
update needs to be installed on applicable
computers.
—Randy Franklin Smith