Legacy NVIDIA sterepscopic 3D drivers may remember an option in the Control Panel to set the screen size. In the new 3D Vision drivers, there is no such option. Instead, the size of the monitor is automatically chosen when a 3D Ready LCD panel is detected by the drivers. Its size and specs are then recorded in the operating system's registry.
The value MonitorSize in the image above represents the normal value for a 22" Samsung 2233RZ monitor. The value in HEX is 2C, and in decimal, the value is 44. This is purposely double the size of the monitor with good reason. Each increment represents half an inch in size, so 44 represents a 22-inch monitor. It was done this way so the sizing would be more accurate.