Tricked Out

I know some web sites offer free mp3 ringtones, but u still have to pay for the media net in order to download them. I read that with the nokia 3330 you could set your mp3 songs as your rigntones. How do you Get them from the computer to your phone. I want a phone that I can burn cd songs to my comp and then transfer them to my phone as mp3 ringtones without having to pay anything. Is this possible? Let me know if it is and what phones have this feature.