[Rob]

For the home user, you might be prepared to take the risk and set your A?V to update manually, or at an odd time of day so it doesn't interfere with your gaming. A major factor in that is whether you are disciplined enough not to open email attachments, which are the primary payload using all sorts of social engineering tricks to entice the user to get the virus onto the PC. Once you have had the inconvenience of a virus attack, you will happily sacrifice a blip in your online gaming or whatever, against a day or more of restoring your 'puter.

A major factor in how often you need to check for updates is the amount of email you handle. The more contacts you have, the more probable one of your contacts will get infected and unknowingly send you something (that neither you contact or you is aware is being sent).

In business environments, the situation gets even worse. My office has 11 users. Today alone we received 20 virus infected emails. That's why our ofice A/V is set to check for updates many times a day.

However, most of the dodgy emails are our residential based cleint. The dodgy emais often spoof their email addys. Whilst rapid virus propogation needs corporate networks, residential users are the weak link in virus prevention.