Hiya,
Again just to go on with what Lisa and Marcus have said. Using Flash and Slideshow Pro is probably one of your best bets as they are ‘fairly’ secure in the way that they deal with images. With Slideshow Pro you don’t have to allow the images to be clicked to go larger so that will help on one level. Also if you don’t make the images in the Flash file too big then they also won’t be of much use to anyone.
Unfortunately if someone really really wants the images or the location of the XML file then this is actually really easy to get. In Safari for instance if you go the ‘Activity’ window then this will show you all the links that are loaded into the current page(s) that are open in the browser. From this you can find out all the information you like. The only way (I think) that you could really protect images (other than screenshots) is to use an Applet but I would really really advise going down this route as personally I think they are very very old fashioned and can slow an awful lot of computers down.
As others have said if you can view it on the screen then you will always be able to get the image at screen resolution even if it is just by a screenshot. I don’t think there will ever be a way around that but I don’t think there are too many people that are going to be wanting to do that anyway and even if they do then they are only going to be able to use them on the web and not to print as the resolution is just way too low.
If you make sure that your photos are well copywritten as I’m sure they must be if a professional photographer has taken them then you shouldn’t really have too many problems.
Hope this all helps you decide on what to do with the images and wish you the best with everything.
Best wishes,
Mark