If you're talking about older systems with sequenced (midi) music, it might not be as hard as you think, as there are already extracted sets out there you can just convert to mp3. I have a set of loose instructions i posted a while back that referred to .spc files but works for most older systems:
http://forums.ffshrine.org/showpost.php?p=1365965&postcount=4
If you're talking about ripping the music directly from the game, there are different ways to do it ranging from dumping it from the rom with an emulator to line-in recordings, although the latter seems to be frowned upon? Anyway, I don't know much about these methods as there are multiple dumps of older games available online already (most of the time.)
Hopefully this applies to what you were asking and I'm not answering a completely different question. Good luck!
This is exactly what I meant. I had no idea that converting these music formats to mp3 was that straightforward. I was able to get it working without much trouble at all. Maybe something like your post should be stickied in the main music forum.
Also, another note for anyone who might be reading: the default LAME settings for mp3 conversion has a low bitrate. If you're a stickler about bitrates, use foobar's preferences menu to edit the LAME comand line parameters.