Avast is a good anti-virushttp://www.avast.com/eng/download-avast-... [Free home edition]Avira is also a good anti-virushttp://www.free-av.comWindows Defender is recommended in addition for real-time spy-ware protection.http://www.microsoft.com/windows/product...Download SuperAntiSpyware for user initiated scanshttp://www.superantispyware.com/superant...Remember to only have one anti-virus installed on your PC