This popped up on my machine a few minutes ago, and it did NOT want to be closed. Here is the scoop on it; more info available if you click the link.
XP Antivirus 2009 is classified as a rogue scanner, sometimes referred to as scareware. Rogue scanners masquerade as antivirus, antispyware, or other security software, claiming the user's system is infected in order to trick them into paying for a full version. In some cases, users who pay for the full version of a rogue scanner product will end up with erroneous charges on their credit card after purchase. For example, a rogue scanner may claim the price is $49 but the charge that appears on the credit card may be as high as $190 or more.