A LONG story - Question is: which registry key should I edit?

I have a problem I cannot solve myself.

After REPAIR of my WinXP Home SP1, I had problems with Office 2003 SP2. It
was related to Windows Installer. It losted info about Office installation
and it was not possible to repair it from original CD.

A. I was told I had to cleanup by an MS utility the WinInstall registry
entry and reinstall Office 2003 and reapply it. I did, it worked.

However, when I tried to apply all the updates it did not work. The reason
was that I also had a very small component of Office 2000 Premium: the Art
Gallery.

B. So I applied Office 2003 SP2 manually. It worked.

Then I had to fix the Office 2000 problem too. So I cleaned up also that
installation, but when I reinstalled Office 2000, it installed the whole
package, not only ArtGallery. I had to expect that, but I realized only when
happened.

C. So now I had both Office 2000 and Office 2003.

I did a mistake. I opened Word 2000. It automatically did some repair.

D. I disinstalled the whole Office 2000 package BUT the ArtGallery. It
worked.

Now I had Office 2003 SP2 + ArtGallery.

When I launched Excel and the other applications, each one repaired itself.
However when I launched Word 2003 it said that there was something wrong and
that it needed to be repaired. I tried, but it said that it could not find
the origin of data. Again the classic WinInstaller problem! Word 2003 works
fine, but:

1. it gives that error each time is launched
2. I still cannot update from MS site

QUESTION: is there a specific REGISTRY KEY I can edit manually to fix this
problem without cleaning up and reinstall Office 2003 again and all
upgrades?

Dario de Judicibus