just today i tried a freeware program called
Switch to convert an m4a to mp3 32-320kb vbr
(i tried it first with the imTOO converter, but it screwed the 'time' element of the file, it played fine but it said it was 26 odd mins, when in reality it was 5)
its a nice little tool, and it can handle flac files too
change output format to mp3, then change the settings to the same as this..
will be best quality + filesize, then add the files, and click convert!
add the id3 tags yourself in winamp or something