I think I have an amazing idea for a Web site business, but I need some quick advice?

I need to work with some designer friends and Web developers, but before I do that, how can I ensure that my idea won't be stolen? Do I patent it? It's an exciting approach to a Web site business, and I want to tell people, but I don't want to get screwed. What can I do without shelling out tons of money to patent/trademark/copyright something that may not even be made down the line?