Convert mpeg-4 to avi

I am trying to burn a data disc of 13 t.v. episodes so I can watch them on my divx/xvid compatible standalone dvd player. However, one of these files is in mpeg-4 format and cannot be read by my player.(The other 12 are avi’s.) Can someone please recommend a freeware or open source program that can easily (one click!) convert this file to a format that can be read by my standalone once burned as data?
I have tried WinAVI Video Converter and a host of other evaluation versions with no usable results. Thank you.

MPEG-4 can mean about 20 different things, including DivX, XviD, AAC etc…

When most standalone players say they “support MPEG-4”, they usually mean DivX/XviD …
What is the file extension that can’t be read?

Thanks for your reply. I resorted to Dr. Divx and got the job done. Not the quality I was looking for but it’ll do.