Half of UK IT managers say they have no plans to migrate to Microsoft's Windows Vista within the next three years, with just 3 percent intending to introduce the operating system immediately.

Respondents in a survey of 100 IT managers at companies with over 1,000 employees said deploying the new system represented a significant challenge and investment in resources.

The main deterrent to Vista migration was complexity, with 62 percent of those surveyed by automated system deployment vendor Enteo, and technology marketing consultancy Vanson Bourne saying this would make them think twice.

Stephan Glathe, chief technology officer at Enteo, said it was "a shame" that IT managers appeared to be delaying adoption of the new operating system because of fears about migration. "A number of those surveyed were deterred by post-migration issues such as patching, which is understandable. Microsoft has already announced the launch of the first service pack for the product, so many IT managers may be waiting for this to come out before they roll out the new OS."

IT managers were also concerned about security during and after rollout, and just under a third were discouraged by having to manually roll out the software.

The time it takes to make a full migration is another issue, with 49 percent of those interviewed saying the process of preparation, testing, rollout and resolving post-migration issues would take 12 months or longer. A further 45 percent expected it to take six months or more. Only 6 percent estimated that it would take under three months to migrate to Vista.

One of the top concerns was the possibility of downtime for users, and consequently, loss of productivity. IT managers were also concerned that helping users restore their personal settings could take too much staff time. Installing software which will not always visibly enhance productivity, unlike a new application for a project, customer relationship management or enterprise resource planning system, was also a worry.

The research contradicts findings in other surveys, which indicate that despite the concerns over a migration timeframe, a significant number of firms have begun to change over to the new system, and see it as a necessary development for their businesses.

Glathe said businesses should be prepared to put work into adopting the important change. "Realistically, companies need to think about rolling out a new OS as they do about Christmas," he said. "As annoying as it is, you have to plan."

He continued: "Vista represents an opportunity for businesses to gain improved functionality and a generally more efficient OS. However, migrating to a completely new OS is no easy task and IT managers need to be prepared and have the right tools in order to gain the maximum benefits."