Also the thing timestoby was talking about. When you put your mouse in a corner to start up your screensaver. That is called Expose. It is also in your system preferences. Here is how to set it up. Go to system preferences, click on the icon named Expose and Spaces (Expose has an accent on the "e"), then there will be two tabs, Expose should be the default tab. If not click on the Expose tab. Then there is a picture of your desktop and 4 things that you can change surrounding it. Those are your corners. You can click on them and set up whatever you want for that corner. They are limited though. Here are your options (All Windows, Application Windows, Desktop, Dashboard, Spaces, Start Screen Saver, Disable Screensaver, and Sleep Display).