I recommend gui4ffmpeg to convert to dvd from avi
then dvdstyler to author the dvd
then imgburn to burn it
not all dvd conversion ware is the same or even very good, only maybe 3 or 4 for windows are worth using really, most work, just not under all circumstances or do a goood job, some work but are slow and will make you think you have a pentium 100
the above I mentioned are all freeware and ive used them and know they work, and gui4ffmpeg is quite fast and does a good job........its also one of the many thats been ported from linux to windows, for some reason most of the best conversion apps are from linux(go figure)........in fact if you peek inside many of the windows ones you will often see dll's directly from linux just compiled using cygwin !!