Converting & then Burning to DVD

Hey all, hope everyone has had a great easter break.
I've downloaded some shows which I want to put on to disc. But I don't know which program to use...on my pc I used to use convertXtodvd but this doesn't work for the mac so I'm on the look out to buy some new software.

Basically, I need to convert avi/xvid files and then be able to burn them to disc...would love if I could just buy one program for this but don't know what to go for - help please!!

I can't seem to work out iDVD although that's already on my installed on my machine.

Assuming these are legit non-illegal downloads, you can use Toast or Popcorn to do this.

Great I'll pop to PC world later see what I can get