Instructions
Check the inputs on your PC monitor. If you don't have a PC monitor yet, you can choose whatever inputs you want when you buy one. If you do have a monitor, you'll have to work with what you have. Many CRT monitors will have only VGA inputs, while many LCD or plasma monitors will have multiple inputs like S-video, composite, component and DVI.
Buy the necessary video adapter for your GameCube once you figure out which video format you want to use. If you are using composite inputs, you probably won't have to buy anything else. Otherwise, you will probably need to get a GameCube S-video, component or VGA cable.
Connect your GameCube to your monitor and fire it up. You may have to change the input on the monitor if it features multiple inputs to get the game to show up.
Adjust the settings in your game and on your monitor. It may not look right at first, but adjusting the resolution, brightness, contrast and other variables will probably get the image to look much better.