Unthreat Antivirus, it's free and easy use. I've had it for a while and I totally recommend it, you should check it out - www.unthreat.com
you will find free antivirus from many different antivirus sites. but i want to give simple advice you use a register version of antivirus because the benefits of using register version is that you also get help from " Virus Removal Service " team at any time.
ESet Nod 32 Smart Security 5...
Username and Passwords provided almost everyday on Facebook...
Very light on resources.. Reputed virus scanner..
I am not using free antivirus because free softwares having more chances of duplication like Microsoft essential pro. It shows warning message also See this
Good point.. My netbook totally got screwed up on both ends (XP and Win 7). Currently using Malware bytes.. Dont really know which is a good one.
Older version are good, but they cant handle newer risks.. Bit Defender has high ratings for security.. but dont know how it is on computer resources.
Use Protegent 360 antivirus, It is having good security feature along with antivirus.
Microsoft Security Essentials, Avast, AVG - these are my favorites.
Best FREE solution is Bitdefender http://www.bitdefender.com/solutions/free.html