I was going to specifically cite Antivirus only, but since so many people insist that OSX itself is the perfect virus protection...or else blame it on the user, I've decided to include it as well. As I'm frequently busy, I could use some help. I put this together because I haven't really seen any good benchmarks for any of these software. What really needs to be tested are response time, memory usage, disk usage (including all components), usability, and stability. Here's examples why: Norton took 1GB of my SSD...a significant amount of space. Intego Virusbarrier had fun crashing my computer all the time...at least norton didn't do that. There are reports that others sap 100% cpu usage. OsX itself would have left my computer shut down for about 20 or so days until a definition was released...had mac defender been an actual virus. Here's the list so far: Mac Defender Released: ~2 May (it's the trojan) Responses Sophos: 2 May 2011 Intego Virusbarrier V5 & V6: 2 May 2011 MacScan: 4 May 2011 Apple OsX: 31 May 2011 Kasperky: NLT (no later than) 4 May 2011 Norton: iAntivirus: ClamXav: NLT 8 May 2011 Avast: MacKeeper: McAfee: Don't be worried about the fact that some of these have NLT and some later date than others...I simply can't find when they updated their definitions to include Mac Defender.