There are tens of thousands of computer viruses and every day new ones are being created. Developing new viruses (and 'strains' and hoaxes) is seen as a challenge by their 'inventors' who attempt to spread them as fast as possible before they are detected and prevented. Viruses cause frustration, wasted time and lost data and cost UK industry millions of pounds a year.

Most viruses are spread by being hidden in an e-mail attachment. Some viruses don't even wait for you to send an e-mail to someone else but spread to others by sending (without you being aware of it) e-mails to some or all of your address book contacts, perhaps using another name in your address book as the false 'sender'. If there is any doubt about the veracity of an e-mail & its attachment don't open the attachment - the virus in an attachment won't infect your system, and therefore potentially others too, if the attachment remains unopened.

Although they are not strictly-speaking viruses, Spyware (also known as Adware) programs have a similar effect - they take over some aspect of your computer. Usually transmitted via a website you've visited these can be every bit as nasty causing annoying pop-ups to remotely dialing premium rate numbers (the shock comes with your next telephone bill!).

But the potential damage from a virus can be snuffed out at 'birth' by using an effective and up-to-date virus checker on your computer or remotely at your Service Provider, for example. A virus checker on your PC can also remove previously infected files and data, restoring them to a safe and 'clean' state.

Many good anti-virus software packages for installing on PCs are available to purchase, or on subscription, from companies like Symantec and McAfee. 'Automatic' updates are provided to ensure viruses created since the original software was produced are also being caught.

Probably the most effective method, however, is to choose and use a service or Internet Service Provider (eg Tiscali, who also remove spam too!) that traps viruses before they even reach you. By transferring responsibility to before the e-mail is received you won't need to remember to keep your anti-virus software up-to-date (many people forget to do this but you can make it automatic) and you'll save e-mail download time.

Excellent software - AVG anti-virus system - as used by the Editor of SilverSurfers, is available free (as a download) for personal use by UK users. Downloading should take around 20 minutes with a 56k modem (the file is about 6Mb in size) - a small price to pay for peace of mind. AVG anti-virus includes free ongoing updates too. To download AVG anti-virus free click here and select a 'download' link.

For information and advice about preventing hackers getting into your computer please click here.