Can I protect my ideas before getting a copyright? 1 Answers as of August 11, 2010

I have been discussing an idea that I have with my friends and colleagues. Is there any sort of way that I can prove that I had this idea first before getting it copyrighted, so none of them can take it? I guess what I am asking is, is there a way that I can show that my idea existed at a certain time prior to anyone else thinking of it? Do I need to also prove that it was my idea first before speaking with a lawyer? I am fearful (more fearful about my friends and colleagues) that they might also steal my idea.