Originally Posted by rat
I keep getting the ubiqitious "your computer is infected, download this antivirus" virus here. Am I the only one??
Yes. It's only you.
A well written virus is well behaved to avoid detection and you'll never know it's there. If you saw the popup, you're probably not infected.
The stuff that pops up and says "You're infected, download this" is actually trying to get you to infect your own computer because it's incapable of doing the job by itself.
Hit Alt-F4 to close the popup (never click any of the buttons provided on a suspicious form), and you might consider enabling the pop-up blocker in your browser to prevent more of the same. In Firefox, it's under Preferences->Content.