Actually, the question should be: when will Macs start to need security software? It's going to happen sometime, Macfans, and you might as well get used to that fact.
Geoff, the revered IT admin here at PC Advisor Towers, would say 'right now', and insists that all the Macs in the office have up-to-date antivirus, firewalls and the rest. But the key industry journalist sitting in my chair has been running a web-connected, AV-free Powerbook G4 for more than five years, with no discernible downside. And I'm not going to be shelling out any time soon.
Full disclosure: my feelings of security are based more on the relative obscurity of the Mac platform rather that on any inherent, built-in Apple defence. In the past it may have been fair to say that the Unix foundation made the Mac OS X harder to hack, and Snow Leopard has a healthy batch of native security features. But we've seen sufficient proof of concepts to show that it is in no way impossible to successfully attack a Mac. It's just that at this moment in time, the lowest hanging fruit is unprotected Windows machines, of which there are worryingly many.
(Despite the double glazing, security lights and burglar alarm you could, if you really wanted to, break into my house. But as long as there is a house down the street with an open window, you are unlikely to do so. [Please don't, by the way.])
Security vendors such as Kaspersky and McAfee are keen to punt security products for Macs. Of course they are - everyone likes money, right? But as with mobile phone security software, there's no need to make a purchase just yet.
That day is getting closer, though. Complacency is not advised.
The Mac platform now accounts for 8 percent of the users who visit PCAdvisor.co.uk every day: and we're hardly a mecca for Apple fans. The more popular OS X becomes, the more likely it is that online thugs will attack: where there's brass there's muck.
According to an interesting, if apostrophe-heavy, blog posting from AVG CEO JR Smith, a Russian network of spam and malware affiliates has recently been "offering $0.43 for each malicious [Mac OS X] install". Smith suggests that this price tag means the Mac platform is becoming increasingly lucrative to web criminals. And I tend to agree.
My advice? Maintain a watching brief.
Sooner or later, Apple Macs will become a target for attack. And when they do, those of us who run and, yes, love Apple PCs will need to get secure, fast.
Let the guy over the road be the one caught with his window open.
Further reading: PC security reviews, alerts and advice
See also: The 10 best Apple Macs of all time