If one thing pushes you to upgrade your current PC, it is likely to be a new game. Absolutely nothing else stresses a PC quite as much as a modern game running with all the high quality settings turned on. You need a decent processor, plenty of memory and a fair amount of hard drive space, but the really important thing is your graphics card.

At the end of 2002 Microsoft introduced its DirectX 9 technology for 3D graphics, with the emphasis on cinematic realism. The key here is two graphics technologies called vertex shaders and pixel shaders. Previous versions of DirectX would offload graphics work to the processor if your graphics card couldn't cope, but if you don't have a DirectX 9 graphics card you simply won't see the new effects that the games designers have created.

In fairness a DirectX 8.1 card will make an attempt at running a DirectX 9 game, but if you have a GeForce MX or Radeon 128 and you want to play Half Life 2 (when it arrives) then it's time to get a new graphics card.

The most important part of a graphics card is the chip or GPU (Graphics Processing Unit), but the amount of memory is also significant, as are the output ports. If you want to do video capture you'll also need a video-in feature, and let's not forget that most manufacturers will include some software too.

Although you can spend up to £400 on a graphics card, we reckon that most sane people think that £150 is a far more reasonable figure, so we've rounded up seven DirectX 9 graphics cards that sell for less than that sum - and most are closer to £100.

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