There is no *best* security this side of the grave. (For computers, this would mean that once you're sure your computer is clean, disable networking & never load any new programs-then you can be sure it will stay clean.)
To minimize your risks, in computing as well as in other areas of life, your best defense is to be vigilant (some might call it paranoid). Watch what's going on & think about what you'll do before you do it. If pushed to make a decision always opt on the safe side, even if it means forgoing something that, if the choice is legitimate, would be beneficial.
I know some people who don't use *any* anti-virus or firewall & never seem to have problems. That takes extreme vigilance & it's not for me, but I do like a security package that combines decent protection with providing me a good view of what's happening in the background. I don't mind a lot of alerts so I rarely tell it to remember my answers unless I'm absolutely certain. For me, Comodo Internet Security (Personal Edition, i.e. free) works well. YMMV. *Don't* install the free toolbar when offered (you'll need to uncheck those boxes). It used to be Ask.com but now it's called Hotsurf, IIRC. Doesn't matter, you don't need it. (I also don't use their 'secure' DNS servers. I'm sure they're secure, but OpenDNS seems quite secure, too, and IMO works better.)
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I have been looking at Panda's Global Security and it seems to be a really great program with the "In The Cloud" protection and all. 
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