Believe me, it does not work well with just two monitors, for anything really. But...all you need to do is open Catalyst Control Center, and on the advanced control center, select desktops and displays from the "graphics" drop down box. Right click on one of the numbered monitors that is displayed in the middle, and tell it to create group. Then it might ask you if you want to disable desktop. Say yes. Then it will give you the option to change your screen orientation. Click save, and you are done.