I Know this is an old thread, but would like to give my 2 cents anyway
If your looking for the best free option i would use:
* Avast Free
* Comodo Firewall
* Malwarebytes Antimalware
and if your still paranoid you can also use the following:
* SuperAntispyware
and the various online scanners. remeber these dont usually disinfect your PC they just let you know which ones they find. Then its up to you to remove them.
and for regular cleaning i recommend
* Ccleaner
Then once a week, use ccleaner to remove all the extras your PC accumulates like cookies and temp files etc, then do a full scan with both MBAM and Avast.
Always Remeber to update your PC and relevant programs like your Antiviruses, AntiMalwares, browsers, Java and Adobe readers etc.
No Antivirus is 100% good, were always one step behind the hackers. But with regular user attention and diligence we can make it a lot harder. For those who like to download "warez" software, even though your virus scanner(s) say its clean it could well be not. As in todays world, for a small fee hackers can make anyprogram evade all antiviruses. If at anytime your never sure, make a virtual PC machine to run your 'suspect' files.
If anyone wants any help or tips feel free to PM me