Businesses are becoming less reliant on Microsoft's Windows operating system, according to Forrester Research, with deployment in enterprises dropping by nearly four per cent in 2007.

The latest Forrester figures paint a mixed picture for Microsoft: it still has the dominant share of the enterprise desktop OS market, but users in some niches have migrated to Mac or Linux, while Vista deployments are largely restricted to users upgrading from Windows versions nearing end-of-life.

But the report shows that Windows XP use has remained steady, with a small number of Vista deployments representing users migrating from Windows 2000.

Forrester's data comes from monthly surveys during 2007 of the browser and desktop environments operated by over 50,000 users drawn from upwards of 2,300 large enterprises.

During this period, Vista uptake grew from almost zero to being used in about six per cent of organisations. At the same time, Windows 2000 declined from nine percent to three per cent, while Windows XP remained steady at about 90 per cent throughout the year.

Forrester's data shows that Apple's share of the market grew from 1.2 per cent of enterprises at the start of the year to 4.2 per cent by the end. Linux desktop deployments also increased, but remained at less than one percent.

The author, research director Thomas Mendel, concluded that Microsoft's dominance of the enterprise desktop is secure, but warned that economic conditions and a lack of enterprise interest in Vista could stall uptake of Microsoft's latest platform.

"One quarter of enterprises have scheduled 2008 deployments, but given the slow start, little gain in productivity, and the timetabled release of Windows 7 in H2 2009, businesses may decide to pull back rollouts or skip the version altogether," Mendel wrote.