Copy the following line before the end of your body section.
It fills the area (named picsaver) previously defined with the transparent gif image (named pic17.gif).
If the image is in another directory than your page, you have to add the path (something like "../images/pic17.gif".
If the area to hide is smaller or larger you have to adjust the height and width values.
before
I tend to use the right-click to open image links in a new window (to avoid a slow re-navigate back to an index page) and I find the right-click interceptors really annoying. Especially since if I really wanted to steal the images it would be easy regardless of the above steps!
The invisible gif trick is quite clever!
However I'm sure you're aware it would be pretty trivial to write a tool to circumvent all the above steps if someone was determined. A more tamperproof solution might be to use something like Flash to host your slide show/image gallery -- that would stop `em! Though of course it's much more heavyweight and requires the viewer install a plugin at some point. Plus you'd have to buy the authoring toolkit.