Other common solution is installing QuickTime, although if you don't want to install that program or if what you need s to convert the file, the solution is called Pazera Free MOV to AVI Converter..
I think that the name of the program explain its function very well, doesn't it? It's a free program that allows you to convert MOV to AVI.
The process is very easy and fast, just drag and drop the AVI files and wait a pair of minutes (it depends on the length of the video) while Pazera Free MOV to AVI converter converts the file.
Of course, you can adjust some parameters before converting the files to adjust quality, resolution, audio,...
It supports Windows NT/98/Me/2000/XP/2003/Vista.