int GetSystemMetrics(int iMetric)

  This function retrieves information about the underlying hardware.

Parameters and Return Values
  iMetric can be one of the following identifiers :
        SM_CXSCREEN     - returns the number of columns of text that the
                        current video mode supports.
        SM_CYSCREEN     - returns the number of rows of text that the current
                        video mode supports.
        SM_MOUSEPRESENT - returns TRUE if a mouse is installed, FALSE if not.