Worldwide PC unit growth is projected to be slightly weaker in 2011 than the previous projection, according to Gartner, Inc.'s latest forecast. PC shipments are expected to grow 9.3 percent in 2011, reaching 385 million units. This is slightly lower than Gartner's previous projection of 10.5 percent growth for this year.

Throughout much of the last decade, PC unit growth was powered by consumers. With consumers from mature markets maintaining a tight rein on their spending in response to continuing economic uncertainty, and a lack of compelling reasons for consumers in general to replace their PCs, PC unit growth has slowed and must once again rely on businesses to drive it.

"Consumer mobile PCs are no longer driving growth, because of sharply declining consumer interest in mini-notebooks. Mini-notebook shipments have noticeably contracted over the last several quarters, and this has substantially reduced overall mobile PC unit growth," said Ranjit Atwal, research director at Gartner. "Media tablets, such as the iPad, have also impacted mobile growth, but more because they have caused consumers to delay new mobile PC purchases rather than directly replacing aging mobile PCs with media tablets. We believe direct substitution of media tablets for mobile PCs will be minimal."

PCs are transitioning from a one-size-fits-all computing platform to a more-specialized device, prized for its ability to complement other devices. "The PC market is experiencing dramatic structural changes," said Mr. Atwal." Moving forward, PCs will no longer be a market by themselves, but part of a larger device market that ranges from smart televisions to the most-basic-feature phones. Within this market, consumers and professionals will increasingly use the combination of devices that best suits their particular needs."

Over the next 18 months, PC growth will be supported by healthy professional replacements. "Businesses sharply reduced replacements and extended PC lifetimes in response to the recession," said Raphael Vasquez, research analyst at Gartner. "Businesses have begun replacing aging PCs more vigorously. We expect the growing urgency for businesses to migrate away from Windows XP will drive significant professional replacements."

Gartner has reduced expected 2011 Japanese PC unit growth to 2.4 percent in response to the March earthquake and tsunami. "Desk-based PC shipment growth has been significantly affected and business continuity plans are accelerating the shift to mobile PCs and alternate computing models," said George Shiffler, research director at Gartner. "However, the impact of Japan's twin disasters on worldwide PC shipment growth has been minor, and PC vendors have so far managed the threat of Japanese component disruptions."