Yup...it appears that you are right about the N4. Even though the manual and catalog specs are worded oddly, I think in those instances where they say "DVD-ROM" they are referring to any DVD disc, whether it be "ROM" or "-R", etc. Probally because most people who aren't really into technology would read that and think that "DVD-ROM" means any dvd disc.
So if anyone is reading this thread, it appears the answer is Yes the N4 can play mp3's burned to a dvd disc. Also on another note I think that it's awesome they have added the ability to play DIVX files!!
And back to my original post: I