The best security against malware is safe browsing habits and keeping your Mac up-to-date with securities patches. Apple does not assist AV developers in any way shape or form. The Mac products, even then ones with household 'windows' credibly have had none of this, and most if not all their claims are misleading on their sites. The argument that they are needed to protect the Mac or worse protect your windows systems or MS networked devices are outright laughable as Windows AV products have had decades to mature, far more development, far more R&D dumped into their development and most of all cooperation with Microsoft.
From slowing down OS X to causing outright kernel panics. A litany of anti-virus products have been exposed on these forums for the problems the exacerbate.
