It can happen to the best of us. One day you look across at the computer on the workbench and it starts to resemble one of the dinosaurs so beloved of your Year 2 pupils: clumsy, plodding and out of place. Yet yesterday it appeared the height of technology.

There are two possible remedies: you could buy a state-of-the-art piece of technology; alternatively, you could upgrade your system.

Magazines are full of adverts offering plug-ins and add-ons to transform your machine into something special. Knowledge is the key to success. Consult a reputable education dealer. Most, certainly those for the Acorn range, will be pleased to advise you about what is worthwhile and will offer a fitting service.

Stalyhill Infant School in Stalybridge, Cheshire, has upgraded its A3000 computers. Last year it was struggling to get the best out of its four-year-old machines with one megabyte of memory and single floppy-drive machines; this year it owns two megabyte computers each with a 240-megabyte hard drive. It cost Pounds 275 per machine spread over two financial years.

The first improvement was to update the operating system and double the memory. This allowed the computers to run those innovative programs that demanded more than the existing memory. The second step was the installation of internal hard drives. This meant that the desktop could be configured in a user-friendly form and a variety of software was always accessible with just a click of a mouse. No more scrabbling about in the box of floppy discs while the queue of children with queries grows.

Although initially sceptical, the school now finds the machines much more accessible to staff, which, in turn, has increased the opportunities for pupil use.

The benefit of upgrading is that it costs less than buying a new machine and it should enable you to extend the useful life of your computers. If you need one particular enhancement, an upgrade can be cost-effective. An external CD-Rom drive with interface can be found at about Pounds 200. Hard discs or extra memory are cheaper. However, before being carried away by upgrade fever, think carefully whether the money would be better spent on a new computer as the cost of multiple upgrades soon adds up.

You also need to be sure that your computer can be upgraded to do what you want. Computers that were at the low end of the range when new may not be suitable.

In specifying the requirements for your upgraded system, do not automatically plump for the lowest cost. Prices do not vary in a linear manner and you can usually find something much superior to your minimum requirements for little extra cost. Stalyhill found that its new (240-megabyte) hard discs were only Pounds 30 dearer than those of half the size. Hard discs are available in a variety of sizes so it is worth calculating to a cost per megabyte to find best value for money.

You must ensure that you can afford to have your computer out of commission for a few days when you upgrade. Once you have fitted a hard drive you will need to install your software and check that everything runs properly. Installing software in bulk can take hours, so leave yourself plenty of time.

Upgrading will not provide the refinements of a new computer but if processing speed is not a prime requirement, it can offer a cost-effective way of keeping your existing computers at a high standard.

* BETT CONNECTIONS

Castle Technology - stand 439

Simtec Electronics - stand 455

Davyn Computer Services The Workshop, off Princess Street, Sandal, Wakefield, West Yorkshire WF1 5NY. Tel 01924 258036