Hewlett-Packard grabbed a bigger slice of the worldwide PC market in the first quarter, as No. 2 Dell, which is struggling to regain its footing, slipped further behind, a market research firm said.

HP easily outpaced the industry average, increasing shipments by 28.7% from the same quarter a year ago to more than11 million units. Dell, on the other hand, shipped 8.7 million units, down 7.8% from a year ago, Gartner said. In terms of market share for desktops, notebooks, and x86 servers, HP rose to 17.6% from 14.9%; and Dell fell to 13.9% from 16.4%.

Overall, global PC shipments rose by 8.9% year to year to 62.7 million units, Gartner said. Microsoft's launch of Vista in January had "very limited" impact on demand worldwide. Vista adoption was primarily in the consumer and very small business segments in mature market regions, such as the United States and Europe.

In the United States, Dell held on to the top spot, despite a 15.5% decline in shipments to 4.1 million units. Shipments from No. 2 HP rose 25.8% to 3.8 million. Dell's market share fell year to year to 27.9% from 33.9, while HP's rose to 25.7% from 21%.

Dell's <"http://www.informationweek.com/showArticle.jhtml?articleID=197700607">poor performance was expected, given that it's undergoing a major restructuring led by founder Michael Dell. Dell returned as chief executive this year following the resignation of Kevin Rollins. "The first quarter of 2007 was a transitional quarter for Dell as the company began a major restructuring project," Gartner analyst Mikako Kitagawa said in a statement.

Rounding out the top five vendors worldwide, along with market share, were Acer, 6.8%; Lenovo, 6.3%; and Toshiba, 4.1%. In the U.S., the top three vendors after Dell and HP were Gateway, 7.7%; Toshiba, 5.4%; and Apple, 5%.