Do what NitroExplodes said, but take note of this: The size of your monitor will not effect it. I will explain why.
If you are playing the game in 800x600, on a 10" monitor, there will be 800 pixels (in layman's terms, one dot of color) going one way, and going the other way there will be 600 pixels. In 1024x768, it will be 1024 pixels by 768. If you then play the game on a 14" monitor, the pixels will just be streched out, making there be the same number.
The concept is just like watching TV on a 13". Then watch the same show or movie or whatever on a 50" TV, you don't see anything more, but instead it streches the images and makes them larger.
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Hey, SFGAm management, can I buy a couple cages of Sky Whirl?