Before anyone says it is not needed. I do a lot of interactions with other people who have Window's computer. I really don't want to send files or emails to them and infect them. Plus, I do want piece of mind, especially that there are more virus attacks lately on the Mac then there ever has been. But that is another discussion. Here is what I need from and A/V. 1. Very light, like it is not there. I don't want it to bog down Firefox, Chrome, the computer itself etc. 2. I use Outlook 2011 mail, so I need mail that comes in be able to be scanned for Virus right away. 3. I would like to be protected will I am surfing on the web and installing programs, etc. Here are some of the choices. All of these seemed to be updated for Mountain Lion. I purchased last year VirusBarrier X6, and I believe it has slowed down the Mac a good amount. Even though I already paid for it, I am looking at other options , paid or free. 1.ClamXav (free) 2. avast! Free Antivirus for Mac (free) 3 Sophos Anti-Virus for Mac Home Edition (free) 4. Intego VirusBarrier X6 (paid) 5. Kaspersky for Mac 6. Any other that I missed? I am looking for some advice. I really don't want to install everyone of these until I find one that works. Please let me know what you think?