Virus blocker?

[question everything]

I think that some years back I asked and got some suggestion about blocking viruses or malware..

But if I downloaded it, I am not sure where it is on my computer or what would be the name.

I think that a correspondent of mine got his email hacked since "he" sent me a link which I clicked. Just sent me to a story on CNN about some new pills - I got out immediately. So I think it was more of a spam than an attack.

Happened to me twice in the past two weeks, again by someone whose name I recognized. Either way, my spouse suggested that since my Mac is old, using an old OS 10.6.8 no one wold bother to develop a virus. Hope so.

Thus, any suggestions about a virus blocker for the Mac would be appreciated.