Dell Inspiron 1520 (Mid 2007) - Manual (Page 85)

Using Multimedia
85
Windows Vista
1 Click the Windows Vista Start button , click Control Panel, and then
click Appearance and Personalization.
2 Under Personalization, click Adjust Screen Resolution.
The Display Properties window appears.
3 Click Advanced.
4 Click the tab for your video card.
NOTICE:
To determine the type of video card installed in your computer, see
the Windows Help and Support Center. To access the Help and Support
Center in Windows Vista, click the Windows Vista Start button
→ Help
and Support. Under Pick a Task, click Use Tools to view your computer
information and diagnose problems. Then, under My Computer Information,
select Hardware.
5 In the display devices section, select the appropriate option for using
either a single display or multiple displays, ensuring that the display
settings are correct for your selection.