How to format avi videos to be able to burn a DVD on windows vista DVD maker?

I had a tech repair my pc. He must have default all my programs because I was able to download videos in avi format and be able to burn it on a disc and be able to playback on all DVD players. Now when I want to burn a avi format video it reads error. On my laptop I can do it and I was able to do it on my desktop too. Can someone please help