I'm biased but the iPod is the best digital music player on the market. The numbers back me up even if the PC people disagree. it's made by Apple.

I have the Fm transmitter from Belkin and the iTrip. Neither impress me. The tape deck connection sounds best so far, though line in is the best option.

I also know there are a couple of decks out there with line-in in the front and some with line-in in the back in which they (Best Buy at least) will run a line where ever I want it to end up.