Malwarebytes can remove Antivirus XP 2009. Usually the malware is designed to detect malwarebytes running and kills the process. If you download it, rename the file before installing it. Then dont instatlly run it after installing, go to where you installed it, find mbam.exe i believe it's called and rename to something like xma4.exe, run it update it. and you should be good to go.
http://www.malwarebytes.org/