To open Display, click Start, click Control Panel, click Appearance and Themes, and then click Display.
Selecting the Extend my Windows desktop onto this monitor check box allows you to drag items across your screen onto alternate monitors.
Or, you can resize a window to stretch it across more than one monitor.
To use the multiple monitor support feature, you need a PCI or AGP video adapter for each monitor. If you have an onboard video adapter (one that is not a plug-in card but is part of the motherboard) that you want to use as part of a multiple-monitor configuration, it must be set as VGA.
For a comprehensive list of hardware supported by Windows operating systems, see Compatible Hardware and Software in Help and Support Center.
If your computer doesn't recognize your second monitor, click Display Troubleshooter for more information.
The operating system always needs a VGA device. The computer's BIOS or EFI detects the VGA device based on slot order, unless the BIOS or EFI offers an option for choosing which device is to be treated as the VGA device.
The VGA device cannot be stopped, which is an important consideration for docking units.
The monitor that is designated as the primary monitor will display the logon dialog box when you start your computer. In addition, most programs will display windows on the primary monitor when you initially open them.
If you are using Dualview, skip steps 2 and 3 above. Just plug your second monitor into the video out port on your portable computer, or into the second video out port on your desktop computer. When you turn on your computer, it should recognize the second monitor. Follow steps 5 through 7 to extend your display to the second monitor. If the second monitor is not shown on the Settings tab, you might need to update your display driver.