Computers: Playing your cards right: A faster video board puts time on your side - and can allow you to subvert family snaps. Andrew Brown reports

COLOUR, even more than noise, is what makes computers fun to play with. Sorry, that sentence should read: 'Colour is crucial to communicating in a modern business environment'. Games look pretty silly in black and white, too. But upgrading a machine's capacity for colour is really something that pays off for Windows, the PC-compatible's graphics- based operating system. Few games use more than 256 colours whereas almost any desktop is improved by being painted in one of 16.7 million shades.

One of the most popular ways for manufacturers to economise on a Windows machine is to use an insufficiently powerful 'video card'. This is the circuit board which connects the main part of the PC to the monitor. There is some excuse for this frailty, since the appetite of uses for colour seems practically insatiable.

I am running a machine at home with 65,000 colours available at high resolution (give or take a few hundred) and 16.7 million at lower resolutions. This is in one sense quite absurd. It seems impossible that there should be 65,000 different dots on the screen to colour in, even at the highest resolution.

In fact, there are 786,432 of the little brutes all demanding that decisions be made about which of 65,000 colours they should be; and this more than anything else explains why, whatever video card your PC is fitted with, it could probably be speeded up with a new one.

The actual numbers do not matter much. What matters is that it is a time-consuming chore to work out which colour what dot should be. And the larger the screen, the finer the detail; and the more colours, the more work is required of the video card. Nothing except adding more memory will so quickly speed up a Windows computer as putting in a faster video board.

There is a bewildering number of them on the market, ranging in price from about pounds 100 to anything you wish to pay. I chose one by the simple route of reading the computer magazines to find what had come top in their tests. That way I ended up with an Orchid Kelvin 64 with 2 megabtyes of memory on the board. By comparison, the first computer I tried to run Windows on was a laptop with 64 gray-scales instead of colour and 2 megabytes of memory in all. I gave that up after timing it at 15 seconds to open a help file.

There is not a great deal to say about the Kelvin except that it is quick and works without fuss exactly as a gadget should. All I notice is that I have far more realistic colours than I had before, and that everything seems to happen slightly quicker. If only all cards worked as simply as this does.

It has opened the door to a wonderful new world of image manipulation, which only requires that I spend another few hundred pounds on more memory and larger hard disks.

If you have a CD-rom drive, a fast video card will allow you to play with your own holiday snaps on the computer. Almost any Boots store in the country will nowadays print your photos on to CD-rom disks in 'Photo-CD' format.

Once they have been digitised, they can be manipulated in all sorts of fascinating ways: cropped, remodelled and recoloured until all the other tourists have disappeared from the beach, except for your own party which is composed entirely of enormously good-looking and evenly tanned young people. Or you could just work through the wedding photographs painting all the Other Side's teeth green. Whatever. There has to be a serious use for it somewhere.

The good performance of the Orchid board is not entirely a matter of hardware. Almost all the video 'accelerator' boards you can buy use chips made by a few large companies like Tseng. The difference lies in the quality of the software wrapped around the chips and the manuals that explain that software.

Microsoft promises that at some stage in the golden future, PCs will be as easy to upgrade and as intelligent about it as Apple Macs already are. But until then, the installation software is at least as important as the hardware capabilities of the circuit board you choose. It must walk you through all the complexities of 'interrupts' and memory addresses; when it changes the special files that the operating systems read when starting up, it should mark and explain the changes it makes, so they can be undone if neccessary. And when it has done all that, it should work.

This last requirement is what propeller-heads call 'non-trivial', meaning virtually impossible. The operating systems need special bits of software, called 'drivers', to translate their demands into language a simple chip can understand. The drivers for the Orchid card are perfectly fine, but for one small quirk: if I switch the main box and the monitor on at the same time, Windows comes up completely black, so that there is nothing to do but fumble around on this darkened screen until I find the Exit Windows dialogue box and click where the yes button ought to be. As soon as the machine has been rebooted, the monitor catches on and works perfectly.

Some people might find that a serious flaw. But it is trivial compared to the things which broken drivers can do. Recently I managed to erase half the Windows files with the help of a shareware program which asked me whether I wanted to 'clean the temp directory', by which it meant 'wipe out the whole system'.

Fortunately, the machine came with Windows on a CD-rom, so I was able to reinstall fairly painlessly from that, with one small exception. The CD-rom contained drivers for many different video cards, as fitted to different Gateway machines. The first four I tried reduced Windows to complete illegibility. It took me three hours to find the right one and get it working. I then changed video resolutions absent-mindedly again and lost the whole of Windows for another two hours.

Other people have had much worse problems. The only real way to guard against them is to scour on-line information services like Compuserve or the bulletin boards maintained by manufacturers to keep up to date with the latest versions of the video drivers available.