One in four UK small and medium businesses (SMBs) now use Linux, and more than half consider it robust enough for mission-critical applications, according to a new study.

Two in five of the 200 IT managers quizzed by research firm Vanson Bourne said they had switched to Linux from Microsoft Windows.

Major reasons cited for moving to Linux from proprietary operating systems were lower costs (38 per cent), followed by performance, security and reliability (all at 23 per cent).

"More and more IT departments are willing to deploy Linux," said Nick Davis, EMEA Linux xSeries solutions sales manager at IBM, the survey's sponsor.

"UK customers are traditionally conservative in IT infrastructure but the survey shows they see the benefits beginning to outweigh the costs of changing."

As expected, Unix was the biggest casualty. Sun's Solaris, Hewlett Packard's HP-UX and IBM's AIX were being displaced in 23, 15 and 12 per cent of sites respectively.

IBM's OS/400 lost eight per cent, while Windows NT and 2003 between them lost 42 per cent.

Iain Davie, business development manager at Morse for IBM xSeries and Linux, told vnunet.com that Morse's experience generally supported the findings. But SMBs were constrained more than large enterprises through lack of resources.

Davie addded that he expected many more Windows NT users to switch next year when support and security updates stopped, and described a potential twofold opportunity for the channel.

"First, we can package solutions to take away any complexity. If they're faster, cheaper and more reliable the customer doesn't care it's Linux. Second, we can help take away the element of fear in changing over," he said.

So far Linux has been used most for file and print, web serving and hosting, caching, email and firewall applications.

But next year 23 per cent of the IT managers surveyed plan to deploy business intelligence and data warehousing, and a further 15 per cent intend to move enterprise resource planning, customer relationship management and other mission-critical applications.

As well as the 26 per cent of SMBs now using Linux, another 15 per cent intend to do so. Only one third had no intention of using it, the survey found. Interviews took place in September.