Thanks to the massive expansion of the internet over recent years, and the huge numbers of people with permanent broadband connections to their PCs, every single person should have effective antivirus software installed on their Windows computers, or be seriously worried.

A new virus is written and released every few minutes, and so personal defences against these malicious pieces of code must be modern, effective and be able to update without troubling the user. Most people now accept the need for virus protection, but a common question is which product to go for in a world where phrases like 'heuristic algorithms' and 'IDS' are commonplace?

A good virus scanner should have several things as standard. The first and most important thing is automatic updates. The best scanner in the world will fall flat on its face if it was released six months before the virus that trashed your PC was written, unless it updated itself and knew about the new virus before it hit.

Secondly is real-time and scheduled scanning, so your computer can check and recheck itself when you're not using it, rather than sit there twiddling its thumbs. Real time scanning means that anything that goes into or comes out of your computer is scanned for viruses as it passes, a bit like a doorman at a nightclub. That's anything on disc, CD, DVD, internet, USB dongles, cameras, iPods or email.

That's the third one - email. All emails should be scanned coming in and leaving your PC. Especially with the massive increase in spam, and the sinister ability to hide viruses in attachments and even the pictures you get in HTML emails. (One way to get round this particular problem is to disable HTML mail in your email program. Just press F1 for help and type 'email format' and it'll tell you how.)

Any programs that don't have these at the least should be left well alone. On top of that, you should look for added extras like firewalls (utilities that only let certain types of traffic in, or traffic that has an invitation. The one that comes packaged with your computer isn't very good), Spyware and Adware removers (these are little programs that spread like viruses but are there to tell you about a product, or worse to track your every move and then report back to their creators) and personal file protection, which is designed to stop any sinister programs that might get through from accessing your bank details.

Oh yes, if you do see anything branded as 'heuristic' or having 'IDS', it's good. Basically, your doorman on the nightclub, rather than just banning people he knows will cause trouble, will get a bit heavy with anyone he thinks looks dodgy. You can tell him whether to ask you before throwing this suspicious character out on his ear, or to do it automatically.

I hope this article will prove useful to anyone looking to purchase, or update their virus protection, and is unsure about what to look for in antivirus software. It is a decision that could literally mean life or death for a computer and its data, and so should be taken before being hit by the marketing hype.