Phew. After much futzing with the intricacies of Data Rescue X, I was able to pull everything off the damaged drive I needed. I think the corruption of the MDB occurred because of some event back in August 2001, as I had a lot of mysterious ghost files from that time popping up in duplicate or triplicate (my first attempt at rescuing data garnered me 6.6 GB of files from a 3.1GB HD that was only 1.3GB full). I then used Disk Format in OSX, which allowed me to erase the volume and install a OS9 driver. That done, I used a trial version of Prosoft's Data Backup to shift all the rescued files over.
I punched my fist in the air like a monkey in a too-tight flightsuit when I booted up off the new disk and the happy Mac face came up, then loaded, then Entourage loaded up where I had left off. Nice. A few minor things don't work--I lost registration codes for some third party software, and some of my aliases don't go to where they should--but it's as if nothing happened. Of course, I just lost a day of work, so time did pass. On the other hand, I didn't have to take it to the shop to get it fixed. Phew.