screen area

I recently bought a 19" tft monitor and am very pleased with it but am
puzzled at a problem I am having with the screen settings.
It is a digital monitor and can take a setting of screen area 1920 x 1080
but if I set it at this then the desktop becomes a bit like a panorama scene
and the task bar, tool bar and sides have to be accessed by scrolling with
the mouse; in other words the "desktop" is bigger than the screen.
I have to set the area at 1280 x 1024 to get a comfortable fit.
My question is, why does a monitor come with a setting of 1920 x 1080 if I
cannot use it or am I missing something?
Can I change some setting so that the 1920 x 1080 will work without the need
to scroll up, down and sideways?
Thank you.