no youre gonna convert your already avi to dvd-video in winavi (it will then be vobs with a couple ifos and bups)
and then you burn that in nero, open the burning rom, select dvd video, then highlight all the files you got from the conversion AND drag and drop them into the video ts folder you see hit burn and youre done
and then you burn that in nero, open the burning rom, select dvd video, then highlight all the files you got from the conversion AND drag and drop them into the video ts folder you see hit burn and youre done