What you need is VirtualDUB ver 1.3c (or 1.4c) that supports Windows ASF files. You can d/l a copy from _http://www.apachez.net/ look in Tools section.
Just load in file, set Audio to Full processingv mode and for compression, select appropriate MP3 format, For Video set to Full Processing mode and for compression, select the DivX codec you wish to use and set its Bitrate. Then in File, hit Save AVI. You will now have a standard DivX shortly.