1280 x 1024 is not a 4:3 ratio screen resolution, you can either scale down the sides of your display so you have black borders on the left and right or get a squarer TFT screen. If you use the full display area on a normal CRT screen your image will be vertically squashed as your glass screen will always be a quarter wider than it is tall... so too must the resolution or everyone will look fat onscreen.
:-)