Graphics cards are also known as video cards or video adapters and they're responsible for putting the images generated by the computer onto a monitor.

The display can be in a range of resolutions. Common ones are 800 x 600, 1024 x 768, 1280 x 1024, 1680 x 1050 and higher, but there are other resolutions, too. The display can use a range of colours from 16 or 256 right up to 16-bit, 24-bit or 32-bit which supports millions of colours. The greater the resolution and the more colours the card displays, the more memory it requires and the longer it will take to draw the image.

Originally, graphics cards simply plugged into a PC's expansion slot but in order to deliver more power, dedicated graphics connectors were developed. Until recently, the port of choice was the AGP (Advanced Graphics Port) designed as a replacement for PCI, but this has now been replaced by the PCI-Express 16x (known as PEG). Some motherboards have two PEG slots allowing two cards to drive two monitors, and multi-card configurations for die-hard gamers.

For programs which require high-resolution graphics that change quickly such as games, you need a powerful video card. In fact, if you're a games player you will certainly want a high-end card.

For less strenuous applications such as wordprocessing and surfing, performance is not such an issue. However, applications which rely heavily on the display such as graphics applications and perhaps music applications whose displays need to be updated quickly in real-time will also benefit from a fast graphics card.

The latest high-end video cards are being designed to take advantage of Microsoft's new DirectX 10 graphics technology which renders images and 3D games in greater detail at high resolutions.

But whatever your application, it's a good move to get a fast card rather than a bog standard one as a slow graphics card can cause a bottle neck and slow down the overall performance of your computer.