フリーでどこまでできるか。
Windows Defender
http://www.microsoft.com/japan/athome/security/spyware/aboutdefender.mspx
avasoft Ad-aware
http://www.lavasoft.de/japanese/software/adaware/
AVG Anti-Virus 7.1
http://eazyfox.homelinux.org/SecuTool/AVG7/AVG701.html
http://japan.cnet.com/special/story/0,2000056049,20101092-2,00.htm