The formula consists of a healthy dose of Internet Explorer hijackings:
Internet Explorer Hijack #1 advertising Antivirus XP Pro
Another Internet Explorer Hijack
Fake Security Warning
A sprinkle of desktop hijacking:
Finally, stir a little Vundo to glue it all together in, and you have Antivirus XP Pro.
Antivirus XP Pro
Unfortunately, Google Trends data corroborates what I am seeing as shown by the graph below. This graph shows a recent increase of activity for the search keyword Antivirus XP Pro.
Google Trends graph for the keyword Antivirus XP Pro
So, if you are one of the unlucky ones who has Antivirus XP Pro installed, please ignore the warnings, and instead use the guide linked to below to remove it for free.