I had to reinstall with the original discs (10.3.7/10.4.0) and then upgrade to 10.4.11. The vCards were left on the original hard drive intact, but when I try to import them, I get the message that "no importable cards were found."

Thanks, fixed it shortly after posting the question (up all night fixing the crash; answer came to me while in the shower).

What I had to do was delete both the Metadata folder within the address book-related Cache folder in Library, as well as the Address Book folder within the Application Support folder, which happens to be found in another "Library." I then transferred the corresponding files from the previous system (which had been set aside during the reinstallation process), reinstalled Address Book, voila, there were my contacts!

It's confusing to have two identically named file folders so close together within the hierarchy, but I guess there is a valid reason for that.