yeah - that's the catch 22. There is a way to do mixed data and music cd's - but I don't recall it at the moment...

okay - I googled a bit. Suppossedly (I haven't tried this) you do your audio CD but DO NOT CLOSE IT - then you add the data as a seperate session. The audio player (in this case your portable MP3 player) should be able to access the mp3's and when you use the CD in the computer you should be able to access the data files as well.