Any idea where to find that "repair" function in XP?
Let me preface my response by saying that the Repair function worked for me, but my only problem was that Word wasn't working and was asking for a Product Key - I had no issue with a Patch reinstalling or whatever your problem seems to be. And my problem was on my laptop, which runs Windows 7.
So I *assume* Repair will work the same way on XP, but I make no guarantees!
You can join that Microsoft Office Help forum and ask your question there and maybe they can confirm that you need to do a Repair.
HOW TO DO REPAIR IN XP
Go to your Control Panel Select Add or Remove Programs It will populate a list of all the programs on your computer Click on Microsoft Office - or failing that whichever Microsoft program isn't working. Two buttons should come up in the right hand lower corner of the grey box that highlights your selection: one that says CHANGE and one that says REMOVE Click on the one that says CHANGE The next popup should give you the option to REPAIR it.
My install of 32 bit Office 2010 on 32 bit Windows 7 on my laptop seems to be working fine. However I had the three patches for Office 2007 also not installing properly and recurring. The patches, (KB2760411, KB2760583 and KB2760588) seem to relate to the document viewer versions of the Office 2007 programs, not the full Office 2007 programs. I've since removed those three and am waiting on MS to figure this out and fix it.