"On paper, Vista is more sound." Not my opinion, but a security expert's.

At least, it's the view of Max Caceres, director of product management at US-based Core Security Technologies, which develops network-penetration testing software called Core Impact. Caceres says that Microsoft uses more advanced security techniques in Windows Vista than Apple uses in its OS. Mac OS X "is still a little immature in terms of security compared to Vista" he reckons.

As an example, Caceres points to the way Vista handles memory management. Information stored in RAM, he says, is "randomized, making it more difficult to exploit". That's not the case with the Mac software, according to Caceres. But, he adds, Apple's Unix roots, more frequent operating system release cycle and apparent indifference to backward compatibility make the Mac "well positioned to change its security model real quickly". Plus, he notes, security threats are a market share issue. As long as Windows dominates the desktop, he predicts, it will attract most of the malware.

But how long will that dominance persist? Mac unit sales jumped 28 percent last quarter, according to Apple, while PC sales languished in single-digit growth, according to everyone.

Although the Mac's market share remains anemic compared with that of Windows, Apple's hardware is showing up more often in businesses. Mitchell Ashley, chief technology officer at Latis Networks' StillSecure operating unit says his company's Safe Access network access control software has always had to deal with Macs. But recently, that has changed from the occasional encounter to an everyday occurrence. "Today, it's a requirement for global network access control [tools] to manage Macs," Ashley says.