I've gone through two FM transmitters (both Belkin) and I hated both of them.
I use the good old cassette adapter now (took my CD player out of my car for this purpose).
ha i've been using this for months and it's always clear: http://www.target.com/gp/detail.html/ref=br_1_15/601-1952704-8352940?ie=UTF8&frombrowse=1&asin=B00093040Y
the boy wants to get me some real-deal harness thing for my jetta though cos there's a company that makes really good ones for vw's.