[jluerken]

I know two methods.

First is a java script that blocks right click.
Second is smarter but harder to implement.

All images should become table backgrounds with a transparent .gif image on top. The only thing users will download is the transparent gif then

Example

<table background="image.jpg" width="200" height="50">
<tr>
<td><img src="transparent.gif" width="200" height="50"></td>
</tr>
</table>

Those methods are not realy preventing people from taking your images.
They still can access them if the look at the page source and download them directly.
You can visible watermark your images if you run a gallery and add an invisible watermark for all other images on your page.