Sound System Suggestions - Time to upgrade

[CND]

I'm the proud owner of a 2002 X5 3.0i Black Sport & Premium package w/53K.

This includes the premium sound system w/DSP.

I have a lot of MP3's that I would love to hear while driving but are longer than what can be burned to a cd.

I do not own an I Pod but am willing to purchase. When we travel I always enjoy music in my room and would love to bring a reasonably sized sound system i.e. I Pod based). My current MP3 player is an IRiver because of the size (I excercise with it).

Any suggestions as to what direction I should take?

Thanks in advance.