Hello? Is this thing on?

You've got your anti-virus package installed and it's greedily sucking up system resources in the background, but is it actually doing anything useful besides blinking and looking authoritative as it languishes in your task tray? You'd have to be crazy to track down and execute a live virus to find out for sure. Luckily there's some middle ground - it goes by the name of the Eicar test file.

This is a plain text file you create yourself by pasting an alpha-numeric string of characters into a Notepad window. If your anti-virus application is paying attention it will detect the presence of the 'virus' as soon as you save the text file to disk and offer to take action to extinguish the supposed threat.

When I tried it at work, McAfee kicked its behind into orbit a split second after it touched my desktop. Nice to know it's not just a pretty face.