Rene GM , Jul 15, 2007; 03:34 p.m.
That's because our screens are landscape, with 16:9 coming into fashion. A centered vertical photo does not look good there. Better would be offscreen with text on the right or left to balance. You cannot count on screens higher than 768 pixels (very few use even 800x600). Even if people found the F11 key, you should not exceed 700 pixels.