ULI I5 t3h h4rdw4r3 GURU!!!1!
Okay, for some reason iTunes still thought that I had the CD-RW drive in the Mac ('disc burner or software not found') instead of the new DVD-RW/CD-RW drive. So, while searching the web for a solution to this problem, I found PatchBurn, which is an app that makes CD-RW and DVD-RW drives available to iTunes and iDVD.
On a hunch, I sent that to my sister, who had been complaining that her external Iomega USB disk burner didn't work under OS X. And 'lo and behold: One drive profile replacement later, she was happily burning a backup of some of her Uni project movies.
I didn't want to use PatchBurn for my burner, though, because it's supposed to work the same as Apple's, and I thought it should thus work right out of the box. So I e-mailed the FastMac folks, and they asked for my system version and then sent me a copy of PatchBurn with instructions. :-)
Now I feel like I actually knew something about hardware. I guess it'll last just as long as it'll take someone to come up to me and ask me what speed my DVD burner is... (Well, one thing I can tell you: It's fast. Just burned an audio CD to take along in my DiscMan, and was surprised when it was finished after a couple minutes.)