DVDs arent just magical discs you can burn and put into a DVD player and watch the videos you just dled on your computer.
Quicktime can play your avis, but if you burn that to a DVD it wont play.
A DVD is a standard of data and you have to format a DVD to play in a set top player.
A music CD can be made from MP3s but you have to convert them from MP3 to AIFF/WAV in order to make it playable in a stereo. If you leave them as MP3 its simply a data disc of MP3s (which some players CAN read)
in the case of DVDs you have to convert the video to MPEG2 and then AUTHOR the disc.
Toast has this built in, where it will take a video file and make you a generic DVD that will play in any player BUT you dont have any nice fancy menus, cant correct any errors or put in chapter markers etc.
DVD Studio Pro will let you create a DVD, but if you just want to watch some AVIs on a Television consider a VCD. It only holds about 60min of footage but unless your avi is an HD file, the quality is the same. Toast will convert the avi to a VCD and burn you a CD that will play in any DVD player.
DVDs arent simple to make. Never are. That is unless you just want video on a DVD because it can hold 4x the amount of video as a CD, but other than that THERE IS NO BENEFIT to a DVD vs a VCD.