Hey, you can't really fit that much mp's on 128 MB card... And methinks MP3/OGG are such, hum, well known things, that there would allready be player supporting both, if there ever would be.
Besides, there are exellent players for both allready, while I've only seen horrendously few game-format players. SID-player and NSF-player, both lacking in basic player functions. (While the sound is good.) Is there a good mod-player for GP?
Anyways, I, personally, see a HUUUUUGE cap in GP software library, and there's even source for this one, which, if I'm not mistaken should be relatively easy to port.
Ah, the linkin my original post had chanced. Gotta fix it.