You need to set up a custom display resolution from your graphics card settings menu.
If by some fortunate coincidence your GFX card is an ATI/AMD card, simple enter
catalyst control center and go to display and desktop tab, from a list of resolutions
pick the game's resolution which is 800x600, accept. You'll notice the "black borders"
will return. (This is because your monitor is not upscaling that resolution.) Don't revert this change,
instead go to display option and set the current resolution to "fit the screen." That way
there will be no black borders when playing a game with a