Add a second monitor to your PC

If your graphics card has two outputs--the older analog port and the newer Digital Visual Interface (DVI) port--all you have to do to connect a second monitor is plug it into the available port. Newer LCD monitors probably have a DVI port, and that's the one you should make the primary monitor because the picture will be better.

If your graphics card has only one output, you have two choices: You can replace it with a card with two outputs, or you can buy a secondary PCI graphics card, provided you have a free PCI slot. Today, most cards connect via your motherboard's AGP slot. A PCI card may be a cheaper option, but it will be slower--and that's if you can even find one in retail stores, especially one with much more than 64MB of memory, which you would need for heavy gaming or graphics-intensive work on the monitor connected to this card. Opting for a dual-input AGP card gives you the benefits of AGP on both monitors, more video memory, and one higher-quality DVI port.

If you don't have a graphics card and are relying on integrated graphics instead, you'll need a standalone graphics card. If that's the case, you should look for one with two outputs, because when you plug in the new card, the integrated output is usually disabled. Some newer PCs have the faster PCI Express (PCIe) card slots; the x16 slot is for your graphics card. If you're buying a card for this slot, make sure it's a PCIe card.