The previous post is correct, you should have your site registered because if you don't there could be a possibility that the company who copied you will register first and it will come out that you copied their website.
Registration is of utmost importance indeed. You could also try to update your site regularly to prevent people from duplicating it. You could also disable the right click and view source capability of your site so that people can't copy it and its' contents easily.
yeah there is something called private domain registrations..what this means is that your domain admin contact info nd all other infos are kept private..unless i guess theres some real big problem and the govt requests for it..