Richard, who is single and in his 20s, said: "I'd decided to get some music for my MP3 player for a long train journey I had to make.

"I have to admit, I didn't want to pay for it, so I went through a filesharing site."

It wasn't the first time that he had used the site and things were going fine. Until he began to be bombarded with "pop-ups" – irritating messages that keep appearing on the user's computer screen.

"I was shocked. Nothing like this had ever happened before and I just didn't know what to do, so I just turned my computer off."

Richard called a friend who had some knowledge of computers.

"He advised me to take it to a proper computer shop where they could look at the insides of my computer and work out what was going wrong."

After a visit to the computer department of a large electrical retailer nearby, the problem was diagnosed: a virus had been "bundled" as part of the files that Richard had been downloading from the internet.

"Once the virus got into my hard drive it wreaked complete havoc," says Richard ruefully. "I did have anti-virus software, but it was out of date."

The damage to his computer was so extensive that he was told it was beyond repair. "It was going to cost more to fix than to buy a new computer," he says.

"Getting some cheap music ended up costing me an absolute fortune."

Evening Leader computer expert Jeremy Jones, of Jones The Computer in Wrexham, who regularly gives advice on the latest security issues in his weekly Log On column on Fridays, explained how investing in security measures can be money well spent.

He said: "Many people see the cost of internet security as a further unwanted expense.

"But this is frequently a false economy – with the broadband provider costing about £20 per month, and when you consider the initial cost of the PC or laptop and a potential repair bill of £40 or more, it pays to be safe rather than sorry.

"For instance, we supply Bullguard Internet Security at £29.95 per year protecting up to three computers, which offers peace of mind at an affordable price.

"There are a range of free anti-virus products available for download which, although offer some protection, are useless if you are trying to recover from an existing infection.

"What you use your computer for can also make a difference – many of the virus problems we have brought into us are often as a direct result of file sharing/music downloads from illegal sites.

"It also makes common sense to use what is already provided: turning the Windows firewall on; making sure that all security updates are current; and if using Wi-Fi, making sure that suitable encryption is in place."

One thing is for sure, PC security is more important than ever.

The chances are that many of us will use a computer at some point today. Whether it's in the office or at home – writing an important letter or simply surfing the net to see if there are any cheap holidays.

In the last 10 years the personal computer has gone from being an office tool, used to make life easier in business to being an essential part of everyday life, and indispensable in the 21st century world of instant communications.

However, with the increased popularity and use of computers – and the internet – have come many additional risks both to your computer, and to your wallet. Here we look at a few of the common risks and what can be done to protect your computer against them.

Viruses, worms and Trojans may sound like something from another planet, but they are something very real and can do tremendous damage to an unprotected computer.

David Pinel, technical director of IT Pro, a Llangollen-based IT consultancy, has seen many computers that have had to be completely rebuilt as a result of damage caused by malicious software.

"Unprotected computers are a gift to people who want to cause damage," he says. "It is unbelievably easy for a PC to become infected.

Sometimes all it takes is opening an email or visiting a website and your computer can be infected with all manner of malicious software."

This software takes many different forms and can have as many different effects. However, the end result is the same – your PC gets damaged.

While there are many forms of malicious software out there, one of the most well-known is a virus.

"Some viruses are designed to harm your computer by deleting files or damaging programmes, while others are designed to simply be a nuisance – making themselves known through text, video or audio message.

"Whatever their purpose, viruses can damage your computer by using too much of its memory and causing erratic behaviour or a crash."

Trojan Horses – named after the Greek myth – are one of the most common ways for viruses to find their way onto a computer system.

On the outside, they appear to be harmless programmes – maybe a picture or a video – but once inside the computer they run hidden programmes – often giving viruses a way into the system.

Spyware – the name given to computer software which monitors or takes control of the way that your computer works – is a type of malicious software that has emerged, and caused many problems, in recent years.

It collects a wide variety of personal information, from your website viewing habits through to your internet bank details, which could then be used by a third party, sometimes with worrying consequences.

There are many stories of people who have found their bank accounts drained after their accounts were accessed as a result of spyware collecting their details.

For many in rural areas, the internet has become a lifeline, enabling businesses to access customers from much further afield than would have traditionally been the case, and allowing quick and efficient communications.

This means that it is more important than ever that programmes that can cause damage to PCs are kept at bay.

Fortunately, this is often remarkably easy.

"Essentially, it boils down to keeping everything up-to-date," says David Pinel.

"Making sure that your computer has a firewall and antivirus software and making sure that you practice safe internet surfing will all vastly reduce the chances of your computer being infected, and prevention is definitely better than cure."

Go to the next page to read the eight steps to software security