IF it's an original work, once it leaves your typewriter it's automatically
copyrighted. The big question is do you have the money to bring a copyright
infringement suite...and is  your work worth the money and time spent in
doing so? Can you prove how you were monetarily damaged?

Most websites aren't worth copying anyway. What content are you worried
about?

Read more about copyrights here:
http://www.copyright.gov/