Well you aren"t Burning an AVI you are Burning a Mpeg file..The AVI Gets encoded to mpeg so it can be burned..I have Neo DVD and it is a Piece of Crap for Encodeing Quality But the Nero Mpeg Plugin is The Worst thing for encodeing Files to Mpeg...If you want to encode AVI to Mpeg with actual DVD Quality (That is if the AVI is of DVD Quality)then Use a Program that is Made for encodeing Cuz Mpeg encoders aren"t created equal..A Good one for someone that is a Newbie is "Tmpgenc" you can Download it at "
http://www.tmpgenc.net/" it will encode Very high quality Mpeg files..The reason why you didn"t get any Audio from the One you did with NeoDVD is Cuz the audio in the AVI file was Probably AC3 which not many Programs can decode, in Which case you would have to extract the audio to WAV Format and use that as the Audio source, you can do this with a program Called "AVI-Mux"..There are No Good Single Program solutions for Makeing DVD/VCD/SVCD"s from an AVI file to a Burnt Disk in One Program..You usually need a Few Programs and some Understanding of How Digital Video is Made up and the Different Formats of video and audio and there specifications....