The Music Box does rip CDs at 4 or 5 times playing speed, so by the time your CD is on the 3rd or 4th song, it has completed the ripping. Actually, I'm loving the Music Box - works great.
It would be nice to just copy MP3s from either the CF card or from data CDs, but no joy. (Likely Nissan did not want to run afoul of the RIAA attorneys...)
The guys at myg37.com have done some interesting work on the system (same Music Box system is in the G37, Murano, GTR, Armada, Maxima, F35, etc....) They've posted pictures after taking it apart looking for ways to use a bigger hard drive, hacking the nav software, and copying MP3s directly. They discovered some interesting things about the system, but the thread died a couple of months ago with no solutions for copying MP3s or upgrading drives.
Navigation/Musicbox Investigation Part 1 - MyG37
--jayhawk