Yes there was the one that used to pop up messages intended to be by a server. Quickly patched.
One of the best and impartial review sites to get 'FREE' software is Gizmo's Freeware. Here is a link to the anti-malware section but they have sections for everything, educational, office, antivirus, archivers, cd burning, media players, Zzzzzz, Zzzzzz.... and on and on. Gizmo's Freeware Anti-Malware Reviews I hope someone finds this excellent site useful to save a few pennies on software. Regards Flea
This software is not worth purchasing. Not because it is "bad" (it might not be) but because any such software isn't really worth paying for with perfectly decent free options available. Use the free MS Security Essentials (in Win 8 it's already installed as "Defender"), and use a different browser such as Chrome, Firefox or Opera. In the former two, install adblock. Then just be careful where you browse.
So how do you know if you've never used any. I've seen people with antivirus software installed with rootkit viruses on their machine and they are totally oblivious to the fact that their machine is being used to ddos people and relay spam. I remember installing Windows XP (or was it Win2k ?) on a brand new machine which was connected to the internet - without even browsing the internet it got infected within minutes by an exploit.
Better to use free AV like Avast and anti-malware like SuperAntiSpyware/Malwarebytes/Windows Defender.