MPEG-1 to MPEG-4 recoding. Plz Help

[A/\EKC]

Here is the deal - I need to recode some MPEG-1 video to MPEG-4 (DivX). The original file has .DAT extension and playz nicely on Mediaplayer. Do anybody knows how I can do it? I've tried FlaskMPEG, but it doesn't recognize the file as MPEG type (even after I've changed the extension). Any Ideas?
I really appreciate your help on that.