How can I rip a DVD on to my hard drive for free in a common format? (wma, avi, ect)?

I've tried a bunch of programs, and I can't seem to get a usable file that I can watch on windows media player or something. I can decrypt it, but I don't know what to do with those files afterwards.I don't want to pay, or have a free trial, or some stupid water mark. Anyone have any programs that will accomplish this? Windows vista, btw.