I was a junior back then but COM felt like magic to me. I think MS made COM more arcane than necessary. It was not until I read the book Essential COM by Don Box that I understood COM.
"Essential COM" is one of the top computer books ever written and I'd recommend it to anyone who is interested in object systems even if they don't code for Windows. (e.g. I think better than "The Art of the MetaObject Protocol")
I have my copy from before the days when they tarted it up to add to the Developmentor series. I kinda miss Don Box doing his thing, quite an entertaining showman (who remembers Box sitting in a bath on stage talking about SOAP?) and tremendous technical writer.