WASHINGTON — Worldwide sales of personal computers, which had been forecast to decline this year, will instead post modest gains, Gartner research group said Monday.

Gartner said worldwide PC shipments are expected to total 298.9 million units in 2009, up 2.8 percent from 2008. The research analyst also predicted growth by 12.6 percent next year to 336.6 million units.

Gartner had forecast in September that PC sales would fall two percent this year compared with last year.

"Shipments in the third quarter of 2009 were much stronger than we expected, and that alone virtually guaranteed we would see positive growth this year," George Shiffler, research director at Gartner, said in a statement.

"We're anticipating seasonally modest growth in the fourth quarter of 2009, but because shipments were so weak in the fourth quarter of 2008, growth will appear quite strong," he said.

"This could lull vendors and market watchers into thinking the market is recovering faster than it really is," Shiffler said.

Gartner said despite the modest growth in PC sales the market value of PC shipments is forecast to fall by 10.7 percent this year compared with last year to $217 billion.

It said the market value of PC shipments is expected to reach $222.9 billion in 2010, a 2.6 percent increase over 2009.

"Blame this year's drop in market value on the unprecedented declines in PC average selling prices we've seen this year," Shiffler said.

Gartner said PC market growth was being driven by sales of low-cost laptops.

It said mobile PC shipments are on pace to reach 162 million units in 2009, a 15.4 percent increase over 2008, and 196.4 million units in 2010.

Gartner said mini-notebook shipments, which are included in overall mobile PC shipments, are forecast to reach 29 million units in 2009 and 41 million units in 2010.

"Mobile PC shipments continued to get a significant boost from mini-notebooks," said Shiffler.

"We've raised our near-term forecast for mini-notebooks in response, but we have also narrowed our scenarios for them," he said.

"Mini-notebooks are facing increased competition from other low-cost mobile PCs, as well as alternative mobile devices," he added

"They are rapidly finding their level in the market, and we expect their growth to noticeably slow as early as next year," Shiffler said.

Shipments of desktop PCs are expected to total 136.9 million units this year, down nine percent from 2008, and 140.2 million units next year.

Gartner also said it does not expect last month's release of Windows 7, Microsoft's new computer operating system, to have a significant impact on holiday sales.

"We just don't see consumers buying new PCs solely because of Windows 7. We are expecting a modest bump in fourth-quarter consumer demand as vendors promote new Windows 7-based PCs, but the attraction will be the new PCs, not Windows 7," Shiffler said.