I think I've found a solution for my specific problem: getting a mess 'o wav files to load into the 601 LE in a sequence that resembles the explicit ordered file names. I've no mp3 tags and no cue sheets for most of my albums, and the 601 was just shooting them into memory in some unfathomable order.
Somebody a few pages back suggested that *random-order sufferers* try a small desktop application that would reorder the FAT tables by long or short dos names. **I tried to use this application on folders of songs already on the 601, and nothing changed.**
However, after reading some webfo about the eccentricities of dos naming conventions and algorithms, I tried another FAT reordering application. This one works. The key point may be that the files you want to be 'logically' ordered by file name need to be app-sorted while they're still on your computer --> and THEN copied over to the 601. I use discrete folders for albums and mixes anyway.
This suggests that the earlier mentioned application (can't seem to find the name now) may also work just as well, if you sort the files before you transfer them. Or not.
But this one -- FAT Sorter 1.0.4 [http://fenux.net/story/fatsorteroneohfour] -- is free and, so far, working. Knock on wood.