Well, the easiest thing to do is run the game in windowed mode. On the options screen just uncheck 'Fullscreen'.
If you'd like to play it in fullscreen, though, you probably just need to play with you monitor's settings. If you play with the buttons on your monitor, there should be an option called "horizontal position", or something like that, which will let you shift the image back into the correct position. You probably only have to do this once, since your monitor should save your settings after you fix it.