Freeware video converter and DVD burner.?

I have several pieces of video in various formats ( avi, mpg, wmv etc ) on my computer and I have just been given a DVD burner and fitted it in my computer. Could anyone tell me of a good free converting and burning software so that I can convert these video clips and burn them onto DVDs to watch on a normal TV? I don't want to spend money on expensive software just for a few home movies and such so freeware or shareware only please, I already know how to go to PC World and shrink my bank account.