Long ago, I stopped installing Office from CDs. There were too many instances where I was doing something with Office (uninstalling, running it for the first time on a new profile, or accessing some feature) where it wanted the original install CDs. So I started either installing it from the network (for desktops) or installing it from a folder on the HD where I had copied all install files.
I thought that this problem went away with Office 2003 - so it did not ask for CDs after the original install. But twice in two weeks I was proven wrong. These were both on installs I did not do since I still to this day follow my Office install methods even though I had thought they were no longer necessary.
Anyway - in each ocassion, I was doing an uninstall, and it wanted the original install CDs. And of course, the god damn install files are different for an OEM CD and a retail CD. I'm just bitter because today I was doing an uninstall remotely and I had to retrieve about 30 CAB files remotely (I found this site - which was immensely helpful, even though it didn't have quite all the CAB files I needed, the rest I FTP'd to myself) - http://turbidvisions.com/misc/msoffice2003/
So the lesson for today is - keep installing from sources you will always have access to. You won't regret it.