Like you mentioned, an '01 head unit will not accept the ipod adaptor, and of course I could be wrong, but the 03's and later have that feature.
My girlfriend has a FM transmitter for her Ipod Video. I don't know if that's like your "transporter." It works by broadcasting on a FM frequency while over riding whatever station was broadcasting on that frequency. In my car, the sound was quite crisp. However, there was, at times, a little distortion, but I think that was from a bad alignment of the power plug connection to the cig lighter. It cost her ~$80 I think from walmart. I could be wrong on that as i don't really recall.
Personally, since my radio is kaput, I'm thinking of getting a second hand 2003+ headunit and swap it out. Only thing needed, I think, is an adapter for the antenna, but I'm still looking into it.