image sizing question

I'm using gallery v1.5. Call me stupid, but I can't figure this out for the life of me.

I'm trying to configure gallery so it will show images so they fit in the browser window and so you can't view a larger version of the image (even just doing the first would be great). It's for a photographer's site, so we want to make it so people can see the whole image, no matter if its vertical or horizontal and so they can't get a big version to steal.

I turned this option (Auto fit-to-window for images without a resized copy) on in the config and properties of the albums but it doesn't seem to work. Any ideas or tips that might help me out on this or the other question?

(Sorry if this in the wrong forum, I wasn't completely sure where to post).

Thanks all.