Personal recommendations on the order of 
"I use XYZ brand and it works for me" for A/V software are about as meaningless as a politician's promise.
I can run with NO A/V on my system for years at a time and never get a virus or malware. 
My son can can't run more than about two weeks to a month or so regardless of which A/V is installed without picking up something, unless I disable nearly all active content (Java, ActiveX, runtime scripting etc.) and block IM, P2P and social networking sites (which eliminates about 90% of why he wants to use a computer in the first place).  
Close to 90% of your vulnerability comes from your browsing/downloading habits on your Windows system.  Close to 10% comes from whether or not you keep your Windows system up to date with all known patches.  
And when you do the math, close to 100% of your vulnerability comes from running Windows in the first place!  

 (Not that most of us have many realistic options...)
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