You can use music from any source as long as it's not Microsoft or Real. You can also rip all of your current cd's for use on the iPod which is quite simple. Don't use bearshare, if you're going to go the P2P route use Limewire. Another interesting way to get music is to record it off of internet radio with something like stationripper. (oddly enough still legal thanks to a loophole in recording law from the 70's) Nonetheless for best quality get stuff from CD's or Apple music store.

Welcome to the world of Apple. You can't ever go back.

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'84 190d 2.2 - Silver
Converted to 5-Speed
'84 190d 2.2 - Blue
Factory 5-Speed

'76 300D (W115)
Sold, found again in less auspicious circumstances