Microsoft Update unaware of already applied Office Updates?

Post-SP2-Updates for Office 2003 successfully applied in the manner described
in http://support.microsoft.com/kb/829197/EN-US are not recognized by
Microsoft Update: Microsoft Update forces the client to download the Office
Post-SP2-Updates (unless superseded by newer ones) although these updates
were already successfully applied via an Administrative Installation Point,
e.g KB887616,
KB917149, KB917334, KB916518, KB913897, KB905756, KB907417.

However, when downloaded via Microsoft Update Website or Automatic Update,
these updates don't change any office file due to the fact that Office is
already up-to-date: Office Update
(http://office.microsoft.com/en-us/of...e/default.aspx) says "Your
Office products are up-to-date!", too. Particularly our mobile users would
appreciate saving bandwidth if such needless downloads could be avoided. WSUS
cannot be used due to several reasons, the clients running WinXPSP2 get their
Windows Updates directly from the MS Website via Automatic Updates switched
on; the Office Updates, however, are applied via an Administrative
Installation Point according to KB829197.

Why doesn't Microsoft Update recognize Office Updates applied via
Adminstrative Installation Points but in lieu thereof force the client to
download updates which have already been successfully applied?