According to research by Microsoft, more than 2.2 million US PCs were found to be part of botnets, in just the first six months of 2010.

(A botnet is a network of hijacked home computers that criminals use to send spam, phishing e-mails and to launch attacks on websites. They are also used to search the infected machines for information that can be sold on underground auction sites and markets found online.

The really scary thing is the US doesn’t have the highest rate of infections, that dubious honour goes to South Korea where 14.6 out of every 1000 machines were found to be enrolled in botnets. Brazil had the second highest level of infections at 550,000.

It’s really important to protect your computer against these people. Sign up for automatic updates of your software (especially your operating system and browser(s), use anti-virus software (again keep it updated) and run a firewall.

It’s a bit like locking your front door rather than leaving it wide open with a sign that says “Help yourself” outside.)