How do I get rid of malware on windows xp?

My friend has a latop running xp and recently experienced a malware infection, I found someone else had this problem and a user recommended SUPERantispyware from malwarebytes, it got rid of the background title saying it "Your system is infected...". However the full scan crashes when trying to read "C:\WINDOWS\SYSTEM32\RASAP132.DLL". Her background is black with all of her desktop icons all in highlighted in purple. Is there any other free software that can get rid of it or will she have to perform a system restore?|||http://www.microsoft.com/security/malwar鈥?/a>|||Try malwarebytes free www.malwarebytes.org|||http://www.malwarebytes.org/|||try avg 8 freeware or go for norton2009 trial.