I think bitdefender
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I think bitdefender
Avast.
Avast
AVG Free Antivirus
MSE should be fine, or just none if you're careful. I use none on my PC and eset on my laptop (not free).
Personally, I just use lightweight anti-viral protection; therefore, Microsoft Security Essentials is my choice.
Comodo Internet Security
Both AVG and Avast are both good free anti-virus', but they are not great.
It's encouraged just to use common sense when browsing, downloading and sharing, but you will always be an easy target running Windows. Try Avira - lightweight, free, fast and secure.
Also, running anti-malware software by Malwarebytes once in a while, helps to keep you safe. It's also great if you are, or you suspect, that your security has been compromised.
http://www.malwarebytes.org/free/
I also recommend Avast.
Eset SS