Microsoft's delay in shipping its Windows Vista OS (operating system) won't put a big dent in PC sales, although growth for the PC industry is going to slow in the coming years, IDC predicted this week.

The software giant said earlier this month that the pre-installed versions of Vista will not be available until January, although the OS will be released to business partners through its volume licensing programme in November.

"Some consumers will certainly delay PC purchases until Vista is available, but we expect the delay will shift only moderate volume from the fourth quarter of 2006 into 2007 and not cause a loss of sales," Loren Loverde, director of IDC's Worldwide Quarterly PC Tracker, said in a statement.

The Vista delay probably will, however, drive up marketing costs for Microsoft and for PC makers this year, as they try to attract consumers and adjust to the new schedule, IDC said.

IDC's Vista predictions may provide some comfort for PC makers amid a generally cautious outlook.

While PC sales have grown by around 15 percent over the past two years, IDC predicts growth will slow to 10.5 percent this year in most regions. In 2007, growth will nudge slightly higher to 10.7 percent, with 254 million PCs shipped, at a value of $232bn (about £133bn), IDC said.

IDC said it still regarded the figures as "relatively strong". The company had expected a sharper decline in growth, but indications show commercial spending will rise in 2007, prompted in part by interest in Vista.

In November, IDC attributed the overall decline in growth to the end of a three-year buying cycle by businesses and consumers.

In another trend, desktops are losing ground to laptops in the US, IDC said. Consumers are increasingly opting for notebooks, attracted by lower prices, wider screens and improved battery life.

The trend is "stunting desktop PC growth to a trickle" and could allow notebook sales to exceed desktops in the US, IDC said.