The problem isn't really finding a free program to convert. The much bigger problem is finding a free program that will burn a real DVD-structure on a DVD that your player will read.
I remember trying DVD-Santa once and while it is great for converting to DVD, it (at least in my case) made 1 big .vob file (DVD format)
Unfortunately that is not DVD structure that your player will read though. You need something else to do that e.g. IFOEdit
IfoEdit
I have never tried it since I prefer to pay for Nero which does it all.