I remove infections from computers for a living. Avast for the win. Does just as good a job as other good antivirus programs and much better than Norton and McAfee. It also has a boot scan to get rid of those pesky replicators. I personaly don't like AVG because it finds too many false positives and can block and or interfere with legitimate programs. Best free stuff. Avast for antivirus and malwarebytes for antispyware. Spyware Doctor is also very very good but you will have to pay for it. But only 30 buck for three licenses. Try Avast and malwarbytes first. Hope this helps.

http://www.avast.com/free-antivirus-download

http://www.malwarebytes.org/