full, functional DVD playback on Ubuntu 11.10 - how do I make it happen?

I need to get open-source software that will play a DVD movie (one that you'd buy at, say, Walmart) and simply play the movie on my Ubuntu 11.10 computer. No DVD movie player software package offered by Ubuntu 11.10 works. That's it. I've tried every one, gone to the software center, the synaptic package manager, everything but using the terminal. I'm not quite geeky enough to know how. I'm on a fixed income, so I'd rather not go proprietary unless there's no other option. Also, I understand how to enter stuff on the terminal to get results. I just don't know what to do. Any help will be appreciated. Thanks in advance.