Anyone can defeat your "prevent right click" measures by just disabling javascript in their browser - since all of the prevention measures use javascript - and I haven't heard of any prevention that uses another method. Another way that any visitor can "steal" your image is with any screen capture program (such as Gadwin). Basically if you are goingto put your images on the web, anyone who is determined enough can get them for "free" with very little effort.

Watermarks are your only good defense. That is what all of the major stock photo websites use.