Ha, easier said that done. EA figured everyone was just ripping their trax, so they went ahead and secured the .mus/.ast files tighter than a ... well, never mind, its tight enough.
All data is stored in the sdata.viv file in the SDATA folder, but the music is "interactive" which means that while NFSU had a song for each physical block, NFSU2 stores the files across multiple physical blocks. Plus, the damn thing is protected with a lot of data that frankly requires hex editors and some bit of knowledge about their working to bypass to even GET at the .mus files. And once you DO extract them after an entire night's work, forget about converting them into a playable format.
The best thing to do is to plug your PS2/Line Out to your Line In and open a music editing program (Audition/SoundForge/CEP) and then hit Record and then play the EA Trax through the Trax selection in the game. That's what I ended up doing.