If price is not the matter...
If you don't wanna use a portable MP3 player, like the Rio, in conjunction with an auxiliary input on your head unit then you have to take a look @ Kenwood eXcelon Z828 CD-MP3 Car Receiver:
h***://www.edgereview.com/ataglance.cfm?category=audio&ID=279
Had seen it in a magazine some 5 months ago and could not remember its model but only the fact it was a Kenwood. Did a little search and voila...