I purchased CDtoMP3 Maker from Audiotools.net years ago, it was fairly inexpensive and works really well. But if it's freeware you're after, maybe someone else can recommend something? Or click on the Downloads tab, at the homepage of this site and have a look see there.
Most burning programs can use mp3 files to burn regular audio cds. Here is a free one... http://www.burrrn.net/?page_id=4