The simplest method would be to use itunes. itunes will handle all of your mp3's just fine, and will have no problems with the podcasts. itunes includes a burning engine and can burn anything to cd.
This will give you better results than converting the files to mp3.
As a side note, this is not a recommendation of using one product over the other. I have both installed on my system and they co-exist peacefully. :iagree: