Strong demand from emerging markets and an appetite for portable computers, including laptop PCs, has prompted IDC to raise its global PC shipment forecast.

IDC now expects worldwide PC shipments to grow 15.2 percent this year to 310 million units, up from a previous forecast of 12.8 percent growth.

"The increase is due to the revised outlook for portables in which IDC expects a longer run of elevated portable PC growth than in earlier projections," IDC said in a statement. New users in emerging markets are also driving growth.

Shipments of portable computers will rise 34.5 percent this year to 145.3 million units, IDC said, while shipments of desktop PCs and x86 servers will grow just 2.2 percent to 164.7 million.

The revised growth prediction highlights continued strength in the global IT industry despite economic jitters caused by high oil prices, credit troubles in the US and rising inflation.

"Earlier in the year, the US PC industry held its breath regarding the impact of the economic slowdown on PC shipments," said Richard Shim, research manager of IDC's Personal Computing programme. "It's now clear that the [U.S.] commercial market will not see the refresh activity we had previously expected and we have lowered short-term projections as a result. Still, the consumer market remains relatively healthy and the overall US PC market will chug along at decent levels – albeit slower than previous forecasts and other regions – while consumer growth continues."

The Asia Pacific region, excluding Japan, will remain the strongest growth factor for the PC industry in coming years. The region surpassed the US as the region with the largest PC market in total annual shipments at the end of last year. The rest of the world, including Africa, Latin America, Central and Eastern Europe, the Middle East and Canada, is not far behind the US now, according to IDC.

PC prices shouldn't face too much inflation. IDC predicts the value of PC shipments this year to reach $286bn, up 9.6 percent over last year. The figures show that the value of growth in the value of shipments continues to trail unit shipments, despite the fact many people in developing countries are turning away from desktop PCs to laptops, which are more expensive.

IDC also highlighted the new category of low-cost laptops as a factor driving shipments of portable PCs, particularly the Eee PC from Asus and two laptops aimed at children in developing countries, the One Laptop Per Child Foundation's XO notebook and Intel's Classmate PC.

The low-cost category of laptops now meets IDC's criteria to be included in its global PC shipment target because the latest versions of these devices, including their OSs and microprocessors, are more robust than before, the market researcher said.

Global PC shipment growth will remain in the double digits through 2010, followed by high single digit growth through 2012, IDC said. The total value of PC shipments will continue to grow 5 percent to 6 percent annually after 2009 to around $354bn by 2012.