How to convert M4V to AVI?

Hey everyone... I've got some cartoons sitting in .m4v format and I need to convert them over to .avi. I did a little digging on Google and stumbled upon this one program, but after going through the whole installation process, it turns out it isn't actually free. It's just one of those "pay up or get nothing" traps.
Basically, I'm looking for a legit, free program to handle these conversions... thanks...

Format Factory is honestly such a breeze to use—it’s simple, reliable, and best of all, it won't cost you a dime.