Thanks, Brian, System Preferences had it. I was looking for it from the Finder in Applications/Utilities. Everything is just a little different between OS-X and Windows, and I don't remember where to look every time.
My new music files, according to the Finder, are exactly where I think they are. And exactly where I'm telling MC24 to look for them. I tried importing twice, once using auto-import, and once using a single import where I "pointed" to the exact folder where "The Verdict" is. Weird.
To answer your last question, I guess I am keeping MC21 around for exactly this reason; in case something in MC24 didn't work correctly. I was a little surprised that when I upgraded, MC24 didn't delete MC21 during the installation process, so that's another reason for keeping MC21. If I can get those new audio files imported into my MC24 library, I will delete MC21...