While it may not be the greatest stereo, I quite like the stock unit in my 2003 SE-SC. So here are my thoughts for MP3 playback. Please let me know if I'm way off base.

Purchase an RF modulator, one that plugs inline with the antenna, not over the air.

Purchase a Creative nomad (or something like it) with a 20 or 60 gig hard drive. The nomad has a neat remote control with an LCD that displays the songs and let you control the main unit.

Get a custom installer to mount the remote control in the dash somewhere (I think the storage bin under the radio would work). Have them run cables betweem the nomad and the RF modulator.

Any thoughts or suggestions? Any other MP3 players that you would suggest?

Cheers