Hey Empower,
I'm not as experienced as Ric, but from my own experience and that of my friends, I can tell you that the idea is the easy bit.
You can protect yourself somewhat with Non-Disclosure Agreements... but you need to be careful as some NDAs are better than others. Also, if you go public or someone else does, or if the idea is already known somewhere in public, the NDA may lose it's affect. They aren't a guarantee, but if you plan to patent, you need to slap everyone you speak with with an NDA. You can also read the book Ric recommends, and that may help you decide if you should file a provisional application.
It's been my experience that implementation is the really valuable bit, its also the really hard bit that requires many many hours of work. 2 people can start with the same idea, and end up worlds apart.
A saying from the old days was that the surest way to get rich was to "sell spades in a gold rush". This means that the guy in the hardware store is less interested in where you go to find your riches, and more interested in getting rich selling you the shovel. Take care, but don't let paranoia prevent you talking too professionals and learning about the market for your invention.