Update doesn't see installed update (KB887616)

Last month I installed Office 2003 SP2 (KB887616). It was a painful
process as it required me to find an external DVD player to insert the
original Office 2003 software. (Despite the fact that I downloaded the
full 104GB service pack, it still required the DVD to be inserted).

Anyway, yesterday I found three "new" updates waiting for me; one an
update to the OL junk mail filters (KB906173), plus SP2 for the
multilingual user interface pack, and SP2 for Office 2003.

Why does Microsoft Update not detect that the service pack is already
installed? (Help - About shows SP2 for all Office components).

How can I get rid of that update that is already installed?