Forum Moderators: mack
Try looking for a behavior on the macromedia web site for "disabling right click" and look at how they do that. It's not supported across all browsers, but it is possible to do some right click recognition in newer browsers with javascript enabled.
You'll probably find yourself posting in the Javascript forum [webmasterworld.com] here for more specific help. There's some very helpful folks who can help you debug javascript. :)
Befuddled
If you'd still like to implement some protection scheme, here's plenty to read [google.com] about how to do it. :)
In fact, because they are viewing the image, they have already downloaded your image and need only retrieve it from their computer's cache file.
If they are viewing it -- you've already given it to them. :)