Clean XP Antivirus and other fake alert infections with McAfee Stinger
If you've fallen victim to one of these nasty bits of malware, a big repair bill doesn't have to be in your future. There are plenty of great, free, programs you can download to remove fake alert infections. A good one to start with is McAfee Stinger, which they've updated to clean this kind of malware.
Stinger is a free download and doesn't require you to install anything. Save stinger.exe to your desktop, double-click the icon to launch the program, and run a scan. Once it's done, remove any files it detects and reboot your system. That's it! Stinger currently detects and removes more than 1,300 types of malware (including most of the common ones I remove at my day job).
It's a good idea to double-check with another program when you try to clean up an infection like XP Antivirus (or its hundreds of variants). I highly recommend using Malwarebytes -- another free program -- to make sure the malware has been removed.