Vista's new security features will make for such a disruptive user experience that business users might want to steer clear of the operating system for the time being, according to Yankee Group.

In a report published on Monday, the analyst firm said the impact on the way security works in the Windows world will be huge, and will largely eliminate the need for some stand-alone security products, such as anti-spyware and desktop firewalls.

But the new features will make it difficult for many enterprises to upgrade their users, because of usability issues. One problem is that features such as User Account Control, designed to reduce the impact of attacks by limiting users' privileges, are likely to irritate users and IT administrators.

"Although the new security system shows promise, it is far too chatty and annoying," wrote analyst Andrew Jaquith in the report.

He said many people using the tools have said they deliver unnecessarily repetitive messages, have a patronising feel and interrupt administrators' work patterns. He said User Account Control was particularly problematic, for instance forcing users to seek administrator approval for tasks they would ordinarily carry out automatically today. As a result, the feature, which is enabled by default, is likely to be switched off or ignored, Asquith said.

The security features are so annoying that many businesses may want to delay adopting Vista until 2008, continuing to use Windows XP with Service Pack 2 in the meantime, according to Asquith. Companies should also look at other options. "As a hedging strategy, enterprises upgrading their hardware should also take a look Apple's dual boot Intel Macintoshes," Asquith wrote.

Despite the teething troubles, Yankee believes Vista's security improvements will reduce the number of Windows vulnerabilities by up to 80 percent, and lessen the impact of those vulnerabilities that continue to appear.