Many households and offices have a spare monitor or two sitting around. If you fall into this category, you can put that idle display to good use by running two monitors simultaneously, assuming you have Microsoft Windows 98 or later and a little extra desk space. Using two monitors is a quick and inexpensive way to gain more screen real estate because you are able to work on both screens.

Get the right card. To use two monitors, you need to have a second graphics card or one dual-head card such as the Matrox Millennium G550. If you choose to install another card, both graphics cards must be PCI or AGP cards--not the old ISA type. This setup works best if both video cards are the same make, although it's not required. Install the second card according to the manufacturer's directions.

Plug it in and power up. Attach your new monitor to the graphics card that you just installed. To do that, plug cables into the card's video port. Most monitors plug into the (15-pin) VGA port. Next, plug your monitor's power-supply cable into an outlet.

Install the drivers.. When you turn your computer back on, Windows should automatically detect your new hardware. Follow the directions for installing the drivers for your monitor. At some point, the wizard asks whether you have a disk for your new monitor. If you have one, insert it at the right time, then choose the driver. In many cases, you won't need to install drivers because many monitors work with generic Windows Plug and Play drivers. If Windows doesn't detect your monitor, you have to tell the OS to find it by using the Add New Hardware wizard in the Control Panel. If your monitor comes with special software or utilities, install them after you've installed the drivers.

Adjust the settings. When you install a second monitor, you need to designate the primary graphics card and monitor. To do this, right-click the desktop, click Properties, and choose the Settings tab. Choose which display adapter you want to use as your primary adapter, and check the box that says "Extend my Windows desktop onto this monitor."