sorry for the others, but I love the big pics - I got a 22in screen a little while ago, and they look awesome on it. They actually only take up about 60% of the screen. Also, for the rest of you - if you increase the resolution, you'll get more of the pics on the screen, if the computer and screen can handle it.
As for making them smaller - I would assume that using any editing program to make the pics smaller would work.