I found this article interesting, nothing like a security-based company stating their own opinion on which OS is more secure.

From PC-Pro.com:
Sophos says Apple good security choice 2:39PM

Experts at UK security company Sophos suggest Apple might be the best route to security for the masses - that is, until consumers all buy one
UK security company's senior technology consultant Graham Cluley rolled out the damning virus statistics for 2005, showing that with a 48 per cent rise in new viruses, buying a Windows box has never been more risky.

This year saw nearly 16,000 new viruses added to the Sophos database. It's a recognition of the responsiveness and efficiency with which the virus underground operates, using a variety of techniques such as using different packaging algorithms, releasing multiple virus variants simultaneously and tweaking old versions to broaden the scope for successful infection.

Last month saw the biggest slew of new viruses on record, with some 1,940 new signatures added to the Sophos library. And with so much advice and code available online, it's never been easier to add to this list. 'It's kind of like open-source,' said Cluley of the ease with which it is possible to access and edit viral code off the Net. 'There is a problem with too much information being out there.'

And it's the ease with which viruses can now be written in conjunction with a generally homogenous computing environment that is the biggest hurdle for computer security.

Virus writers can now be far more opportunistic. The massive numbers of Windows computers hooked up to broadband connections are a big, big target. Whether it's spamming campaigns exploiting avian bird-flu hype, 419 and phishing scams on the London bombings or public proof of concept code for a software flaw, malware authors can initiate a campaign within hours.

Cluley is full of praise for Microsoft however - particularly for the success of Windows Service Pack 2. 'Microsoft should be applauded for improving its operating system, because it has made the Internet a safer place,' he said.

Plug an unprotected XP computer to the Internet and there's only a six per cent chance of avoiding infection within an hour. Add in SP2 and that figure plummets.

Yet that's clearly not the end of the story. And Microsoft itself is concerned over its own figures showing that barely 30 per cent of customers are running up to date antivirus software.

Cluley too thinks that much of the virus infections are within the consumer rather than business space, with millions of computers running out-of-date antivirus software, if they're running any security software at all.

So something has gone wrong. Two-thirds of Microsoft's own customers are not getting the message and shoring up the systems against the viral tide. No wonder it's bringing out its own OneCare antivirus solution for Windows users.

But perhaps they see it as Microsoft's job to provide a secure platform in the first place, and not their responsibility to dig into their wallets to patch up the bits Microsoft got wrong.

Cluley said that a recent survey it took on the Zotob worm revealed that 35 per cent of the businesses polled thought it was all Microsoft's fault.

But Cluley disagreed, on the basis that it's impossible to guarantee a perfect flawless system. It's the homogeneity that is the problem.

'If everyone used the same antivirus, then that's a disaster too,' he said.

In fact, he thinks Microsoft is now doing such a good job on the security front that attackers will increasingly turn to applications and tools such as Google's Desktop Search as the vector for the next wave of attacks.

'They'll be looking for the add-ons and plug-ins that are popular, and used by lots of people, to find holes in and exploit,' he said.

But there are other options. Plug an unprotected Apple or Linux box onto the Internet, and you can expect to see the infection rate flatline, said Cluley.

That's not to say there are no viruses for Mac OS X or the various Linux distributions, but Windows viruses dwarf them.

'It wouldn't really work for businesses,' said Cluley, 'But for consumers I think [Apple] is quite good.'

You can accuse it of security through obscurity, but in a world where 70 per cent of Windows users don't feel the responsibility of securing their computers, perhaps they are better off with a less targeted platform. Perhaps they don't deserve Windows.
Full article here.