Are you sure. DivX player & VLC are usually very reliable for avi files.
VLC: http://www.videolan.org/vlc/ (choose nearest mirror site) & what it can & can't play: http://www.videolan.org/vlc/features.html & DivX player: http://www.divxmovies.com/players/

Other avi specific players: http://www.itzalist.com/com/avi-player-download.html
http://www.hyplay.com/free_avi_player_download.htm & http://www.karawin.fr/

GSpot will identify which codec you need: http://www.headbands.com/gspot/