Xp security center virus?

My mother downloaded this virus and now i can't get it off the computer. i tried downloading and running this recommended anti virus : a href="http://www.bleepingcomputer.com/malware-removal/xp-securitycenter" rel="nofollow"http://www.bleepingcomputer.com/malware-…/a and it did download successfully, but now the virus wont let me run it. any suggestions?