CNET.com.au has this story from David Braue which looks at the question of whether the Mac is really more secure than other PC operating systems. This is part one:

Apple computers have built a solid reputation on being virus-free, but is the reality different from the image? We look at the security concerns affecting Mac users -- and whether there's cause for alarm.

US health authorities were chuffed recently to announce that canine rabies -- a once common viral infection dangerous to dogs as well as humans -- had been eliminated from the country after not even a single case had been reported since 2004.

A week later, Microsoft put its tail between its legs after it was revealed that its state-of-the-art Windows Vista operating system had fallen prey to Stoned.Angelina, a boot-sector virus that was first seen in 1994 and last seen in the wild in 2001. Nonetheless, up to 100,000 German Medion customers, Virus Bulletin reported, received new computers with the virus on their hard drives. Worse still, the virus went undetected by the bundled Bullguard antivirus software, which had removed the virus definition from its product due to its perceived extinction.

The fact that Stoned.Angelina is still circulating six years after it was last spotted is a reminder of the need for constant vigilance when it comes to system security. It's also a reminder that despite years of effort, the tens of thousands of active viruses currently prodding Windows systems remain a continuous threat.

For people contemplating a new hardware platform, this all adds up to one thing: Apple's Mac OS X, which conventional wisdom holds is impervious to viruses, is a more appealing choice than ever.

Discussions about the Mac-virus issue have raged on for years without resolution, often taking on an emotional aspect from avid Mac fans who recoil at the thought their systems could suffer Windows-like problems.

Certainly, virus-like code -- which is characterised by its ability to replicate itself between systems without human intervention -- has been almost nonexistent on Macs. It was only last year that researchers at antivirus vendor Sophos -- whose Sophos Anti-Virus SBE 2.0 supports OS X -- claimed the discovery of the first-ever Mac virus, OSX/Leap-A (aka OSX/Oompa-A), which propagates via Apple's iChat software.

Subsequent isolated discoveries have unearthed the likes of OSX/Inqtana, a proof-of-concept virus that targets a flaw in OS X's Bluetooth code but has caused no real-world damage. Such discoveries have raised the hackles of Mac devotees, who pointed out that the Inqtana and Leap-A were mainly proof-of-concept viruses and that the Mac community has yet to suffer the crippling effects of a global infection, which these days is spotted by massive spikes in volumes of spam.

Not even the widely publicised Month of Apple Bugs, which highlighted a new Mac OS X exploit every day in January, has done much to damage the Mac's reputation as a fortress of system integrity. Its progenitors were instead criticised for releasing the vulnerabilities to the world, echoing sentiment towards antivirus vendors who, some argued, were launching a FUD (fear, uncertainty and doubt) campaign aimed at winning customers amongst paranoid Windows users making the jump to the Mac.

For recent converts and longtime users alike, the question still lingers: do Mac users need to run antivirus software?

Not really, says Kevin Long, a network and security specialist with Verizon Business Security Solutions and the company's Mac security expert. "The reason is not that there are no security issues on the Mac; it is not impervious," he explains. "But we have seen no replicating viruses on the Mac. And when we talk about risk, we use an equation -- threat times vulnerability times cost -- to figure out the cost of an attack."

Given this method, Long says the risks of introducing still-unstable antivirus software to protect against a still-minimal virus threat are just too great. "Antivirus software doesn't just sit on top of the operating system," he continues. "It has its fingers down deep in there, and if something goes wrong it can foul things up. Antivirus software on the Mac is just not as mature [as on Windows], and every time you put new processes on your system it can introduce stability and security issues."