CricketMX.com

GSpot

Codec Information Appliance

Stable Version 2.21

Gives you all the needed information about your .avi files
So you will have the needed information to easily choose which codecs are needed to play it.

I'll vouch for that. I've used gspot successfully a few times. I mostly share/download music so I don't know heaps about video files. gspot told me all I needed to know tho'. Definitely a good program for those who know that they know nothing.