There is a new SSL vulnerability in the wild that affects the browser, not the server. Chrome & Firefox browsers are supposed to release fixes in the next few days so look out for updates.
Antivirus software is always a contentious question. It seems that there are no right answers: nothing detects all viruses, and everything has an impact on the speed of the computers where it's installed. And there's a tradeoff between these two. My own subjective, biased choices are F-Secure, AVG at a push, and definitely not Kaspersky. Here's why, and some data to help you choose one for yourself.