VSO divx2dvd is an easy to use good quality and fast converter. You can get it in the tools section here www.videohelp.com
never re-encode a video anymore than you have to. It's not only time consuming but lowers the quality. You can vonvert your mpeg4 avi's with the tool I stated above. At the site I stated above you will see the ratings of several free and excellent tools to do what you are attempting. Svcd2dvd is another good one.