http://clairechiang.net/wordpress/?p=14 if you want an explanation on how to rip a DVD. All the software I suggest there is 100% free.
As for turning a widescreen to full screen...that's not a very good idea, but if you really want to, then when you convert a video with Dr. divx (which I explained a little more in my page), you can specify the size of the video, so you can change it to something like 640X480. However, if you do that, then everything will be unusually narrow in the new video.