Super can do this, http://www.erightsoft.com/SUPER.html, although not too many would call it user friendly, it's not that difficult to use.
Where it says "Select ouput container" choose sequence of images.
Set "Output Codec" to Jpeg.
Just remember you will get a lot of jpegs, one for each frame of the video.
Where it says "Drop a valid multimedia file here", just right click and browse to your avi file. When you have the file select "Encode (Active Files). The default output folder is eRightsoft/Super/ouput. You can change that.
If you are not afraid of the command line, there is a program called ffmpeg that will also do the same thing (as a matter of fact this is what Super uses). The command is pretty simple:
ffmpeg -i video.avi image%d.jpg
(where video.avi is the name of your file)