AVI is a generic file extension, divx, xvid annd a lot of other encodings can be labeled as AVI.
A player that is DIVX certified should play divx 3/4/5/6 and some versions of xvid.
Get Gspot (google it) and that'll tell you what the codecs are on an avi file, try burning them and playing them, it'll be trial and error to find out which ones play and a simple matter of using DIVX convertor or DRDivx to reencode them into a certified divx format
