I use my macbook for presentations sometimes. I've got the external VGA adapter, and that works fine whenever I need to use it. What I don't understand is why some projectors appear as an extended desktop and others default to mirror. The mirror one is a pain it messes up all the window sizes and positions, and also may have things (email etc) appear on the projector. Is it a limitation on the resolution of the projector? Is there a way to alway force it to an extended desktop rather than a mirror type setup?