[Pritcher]

Try searching something like "free avi to gif converter" on Google and try out some until you find one that works for you. Most of the things on there will have free trial versions.

I use River Past Video Cleaner with the Animated GIF booster pack for this sort of thing. Some video editors allow you to export to animated gif format too. I know Premier Pro does, but it doesn't always come out so great from there so I generally use the River Past thing.