Mac owners have long been notoriously smug about the lack of viruses for their chosen operating system, but it is far from true to say that viruses do not exist for OS X. In reality, the platform has simply been of little interest to virus writers and coders of malicious software, but the Mac Defender Trojan highlights the fact that Macs are just as vulnerable as other computers. avast! Free Antivirus for Mac is, and there's a clue in the name, a free antivirus tools for Mac -- and a new beta version has just been released. Timing is appropriate given all the noise about Mac Defender.