Oh, also, since the actual mp3 content of the file is the same when it's a FID on your pc, any player should be able to play it if it doesn't get hung up on lack of a .mp3 extension. AFAIK whatever tags it originally had should still be in there too. I think what you might be looking for is a player that has a database component to map your unintelligible file names to real information for the browsing part. Something like foobar2000, or Winamp 5 with the library part installed would do the trick for that.

It'd be some manual work to set up, but it would be tons easier if the files were still all tagged right. After that, you'd browse the library, which would keep track of the fact that "I Will Always Love You" is the file called "1AF30". You'd just want to make sure that it doesn't write anything to the file, because I think the empeg would throw an error if the size doesn't match what it's got in it's database (or maybe that's only for playlists?)