Worldwide PC shipments are expected to increase by 11 per cent this year spurred by uptake in emerging markets rather than the launch of Microsoft’s Vista operating system, according to research.

PC sales are projected to total 257.1 million units in 2007, an 11.1 per cent growth on from 2006 shipments of 231.5million units,

But the study by analyst Gartner says that first half sales show Microsoft’s Vista operating system has not proved a factor in driving new PC sales.

Manufacturers are focusing instead on emerging markets where 55 per cent of the growth is being propelled by new PC use, not replacement purchases.

Gartner expects emerging markets to contribute some 128 million new PC sales during the next two years, consisting of 77 million desk-based systems and 51 million mobile PCs. This will equate to around a quarter of all PC units expected to be shipped globally in 2007 and 2008.

The release of Microsoft Windows Vista operating system at the end of January has, so far, failed to stimulate the market in the way many hoped,’ said George Shiffler, research director for Gartner’s client platforms markets group.

‘Our market data suggests Vista has had very limited impact on PC demand or replacement activity. We don’t see Vista having a significant effect on these going forward unless Microsoft becomes much more aggressive in its marketing efforts.’

Shiffler says that despite a strong demand for mobile PCs, especially among consumers, vendors face challenges in mature markets.

‘Generally weak desk-based PC replacement activity and narrowing penetration opportunities, especially among larger businesses, pose some serious challenges,’ he said.

While desk-based PC shipments are forecast to total 153.9 million units in 2007, an increase of just 2.4 per cent from last year, worldwide mobile PC shipments are forecast to total 103.2 million units in 2007, a 27.1 per cent increase from 2006 with sales driven by falling prices, increasing performance, and the spread of wireless access, says Gartner.