MS Office: Identifying OEM bundle vs. retail

[mickish]

How can I tell whether MS Office was installed from an OEM bundle (e.g., Dell factory install) vs. purchased at the store in a box?

I have already found How to Determine Programmatically If Office XP Is Installed, which says several things are reported in the MS Office Uninstall registry key, but it does not distinguish between OEM and retail versions.

Thanks in advance,

--mickish@eisenworld.com