Typically the game itself will have a method of adjusting the resolution, and that is where you would want to do it.
Just installed Machinarium to my Win XP Pro PC. Game runs fine, but I cannot play it fully as the game fills the screen too much and essential detail is lost at the edges. I have tried adjusting the resolution in 'Display' and I can reduce the size of the screen to where I can see and use the edges, though this also drops the top and bottom edges a bit too far. At the same time though, all my other activities, desktop and what-have-you are also reduced to the point where I am squinting to see what they are. Can anyone show me how to get the right size screen for the game, but to leave other settings untouched? Or is this not possible? Many thanks for all and any help. Regards Walt.