Dell Latitude D530 (Early 2008) - Manual (Page 57)

Using the Display 57
See the documentation that came with your video card for additional
information.
Windows Vista
1 Click the Windows Vista Start button , and click Control Panel.
2 Under Appearance and Personalization, click Adjust screen resolution.
3 In the Display Settings window, click the monitor 2 icon, click the This is
my main monitor check box, and then click Apply.
4 Click OK to close the Display Settings window.