I have Office 2003 Standard (Word, Excel, Powerpoint and Outlook) - upgraded from Office XP (2002). However, I also have Frontpage 2002 and Publisher 2002. Office Update therefore offers me service packs and updates for Offixe XP. When it installs, it only updates the components for Frontpage and Publisher - I know because it asks for the relevant CDs.
Maybe something similar applies to you?