I've been using convertXtodvd. It's really simple and it converts the avi file and burns it all in one program. Let's you create menus, add subtitle (.srt, etc) files aswell. Really easy to use. The version on the site has watermarks till you register it it but I found a hacked version on eMule that I've been using.
I'm new to the whole burning .avi to DVD thing and this has been the best program a newb like me.
www.vso-software.fr/products/convert_x_to_dvd/