Well emily, I'm not a lawyer, but the general concensis is that the poor mans copyright isn't legally useful. Why I don't know, ask a lawyer if you care. Otherwise, don't try it.

That said, you can register a copyright in the US for very little. $25 if I remember right, but it may have gone up. a registered letter is $5 already, so you may as well just go the whole way. Do it yourself copyright kits are avaiable, but your library should have book that contain enough info (the forms are free, just fill them out and send it in.) Just make sure the book on copyrights you check out is recient as the laws have been known to change.