Yes, a copyright exists at the instant you write it down. Registering the copyright is the definite proof to the copyright office that the copyright exists and when it began. In the U.S. the penalties for copyright violation are also much greater when the copyright has been registered. Yes, if you create the work yourself or own all rights to the work, you should put a copyright notice at the bottom. However, search for "copyright faq" and find the correct format. "(c) 2010" is not enough. The name of the copyright holder should be present in a certain place, and I asked a copyright lawyer a while ago and "(c)" is not an acceptable substitute for "©". Sure, you can pay your lawyer to argue (c) or © if you end up in court, but if you use © then you don't have to worry about the judge having to decide that.
Maybe these can offer some additional insight: http://myfreecopyright.com/register http://www.plagiarismtoday.com/stop...ism/your-copyrights-online/3-copyright-myths/