If the Mac’s market share is five percent, then shouldn’t it have five percent of the viruses? It ought to have seen 5,700 viruses last year, not zero. Clearly, there’s something else at work here, and I’ll tell you what it is: Mac OS X is simply harder to hack.
Pogue’s Posts – Apple Changes Its Tunes on Viruses – Technology – New York Times Blog
Check out the entire piece. It is an interesting read. This goes true for Linux as well. 
