Contract work

In fact, t-shirts reading "I caused Vista to slip" soon became common at Microsoft's Building 27, home to the Secure Windows Initiative group. The group is responsible for securing Microsoft's software.

Fathi isn't saying how much money it has spent on making Vista secure, but judging by the contract work available for penetration testers - hacking professionals that specialise in poking and prodding systems to unearth vulnerabilities - it hasn't come cheap.

Although Microsoft will be sponsoring a Vista track at this year's Black Hat hacker conference, many of the most prominent Windows security experts are now under nondisclosure agreements, according to show director, Jeff Moss.

"They've hired pretty much all of the bright people," he said. "So the number of speakers who can actually go out and publicly talk about Windows Vista security has rapidly dwindled."

Brave new world

Microsoft's design choices will have a big effect on Vista's security as well.

Developers have changed the way Vista runs applications, scaling back default operations in order to limit the damage malware can wreak. And they have also changed the way Vista works with computer memory - by fencing off parts of memory and shuffling around the location of Windows functions - in order to make it harder for hackers to trick the PC into running malicious software.

This will make life harder for hackers, but it will also present challenges to users and legitimate software developers as well, who may suddenly have problems running Windows XP code on Vista.

Microsoft downplayed the importance of Symantec's paper. "The issues it discovered were all addressed in Beta 2," a security program manager with Microsoft's security response centre, Stephen Toulouse, said.