Listen to Pochacco, the iTrip really sucks ass, it's the absolute worse signal possible of all the scenarios.
The Tape adapter works best probably, but it looks so ghetto with the wirw hanging out the front of the tapedeck, besides who has a tapedeck installed anymore.
The wireless dock type that charges while it plays works really well also, but it's a houndred bucks.
BTW, if for any reason your battery ever dies hit me up, I changed mine out 2 days ago and it was cheaper than getting a free replacement with Apple and easy as pie to swap out and I didn't have to worry with going without it for a month till I got my replacement.