Viruses are annoying little programs which mess up your computer. In past we've recommended using a resident anti-virus program to actively defend against virus attacks. We had also suggested trying out the google pack which includes Norton Security Scan and loads of other useful software
As a second line of defence, We advice you to periodically check your computer using Free online virus scanners. The following links takes you to the reputed antivirus company sites, which install a small piece of code in your browser(ActiveX/Java) to scan your computer.
