I have some .avi files I'm trying to burn to DVD. I'm a complete noob when it comes to burning DVDs because I just got a MacBook Pro and never had a DVD Burner before.

First of all, only about half of the files worked once the DVD was burned. There is a list on iDVD of videos and the ones that worked once burned showed up with the first scene from the movie on there and the ones that didn't work showed the quicktime icon. I figured it was some kind of bad format so I went into quicktime and exported them as .avi files. (I have divx convertor and toast) After this, they worked fine in iDVD. However, when put in a DVD player, the quality was terrible. I mean, it wasn't all that great before, but this was just atrocious. So, I was wondering what I was doing wrong and how to fix it. Is there some kind of software I need or something? What format should I be converting to? Any help would be greatly appreciated!