hi mike, yep fills the whole screen..i always use the maximum resolution for an lcd screen, its the best way to use them, mine is a dell 19" monitor set at 1280x1024...there is usually a key (on the laptop keyboard) with an alternate function for the display which you would need to press to have the screen sent out only the monitor out and not to both the monitor out and the inbuilt screen...most lappies have it, you just gotta find out which one for you (example on the acer aspire series its the fn key+ f5)
cheers
dennis