If you are running Microsoft Windows and you see popup windows saying that your machine machine contains viruses and that you can use Antivirus 2008 or Antivirus 2009 to automatically clean them, do NOT allow it touch your machine — it is a virus. The best bet is to close the window by clicking on the red X in the top-right corner of the window; you may have to kill the firefox/iexplore process in Task Manager (right-click on the taskbar, choose Task Manager and either use the Applications or Processes tab to End Task the browser’s process).
Many smart people are getting duped by this virus, and it can be difficult to remove from your machine once it has been infected.
The safest thing to do is to become aware of which antivirus you are running and ignore any prompt that comes from a different antivirus package.
If you get infected and need help, let me know and I can direct you to instructions how you may be able to recover your machine. As always, having recent backups of your critical data is a good thing. 🙂