Last year, the popularity of Apple Inc.’s iPad hurt PC sales. This year, that trend is continuing, as new data from two market research firms indicate PC shipments declined in the first three months of 2011.

On Wednesday, Gartner Inc. said that its research shows PC shipments dipped 1.1 percent compared to the same period last year, to 84.3 million. IDC said its numbers show PC shipments fell 3.2 percent to 80.6 million. The companies measure the market in different ways.

Gartner had expected 3 percent shipment growth, while IDC was looking for 1.5 percent growth.

However, Lenovo, the world’s No. 4 PC maker which bases its headquarters in Morrisville, N.C., bucked that trend.

Both firms reported that Lenovo increased shipments by more than 16 percent from a year ago to more than 8 million.

Plus, Lenovo increased its global market share to 10.1 percent, according to IDC, and 9.7 percent, as estimated by Gartner. Both firms had Lenovo had just over 8 percent a year ago., (Read much more about Lenovo’s growth here.)

Gartner principal analyst Mikako Kitagawa said that during the January-March period consumers weren’t as drawn to cheap PCs — usually a category that keeps the market growing. Rather, they were interested in tablet computers and other consumer electronics.

“With the launch of the iPad 2 in February, more consumers either switched to buying an alternative device, or simply held back from buying PCs,” Kitagawa said. “We’re investigating whether this trend is likely to have a long-term effect on the PC market.”

For years, companies tried to popularize tablets, but it wasn’t until Apple released the iPad last April that the category took off. Last month, Apple started selling a new version of the device, and a bevy of companies including Hewlett-Packard Co., Dell Inc. and BlackBerry maker Research In Motion Ltd. are trying to catch up by offering their own takes on the tablet.

IDC attributes the PC shipment decline to several factors, including frugal businesses and a lack of consumer interest. To be successful over time, PC makers must find a better way to sell computers than simply touting their hardware specifications, IDC senior research analyst Jay Chou said.

“‘Good-enough computing’ has become a firm reality, exemplified first by Mini Notebooks and now Media Tablets. Macroeconomic forces can explain some of the ebb and flow of the PC business, but the real question PC vendors have to think hard about is how to enable a compelling user experience that can justify spending on the added horsepower,” he said.

In the U.S., IDC said shipments fell 10.7 percent to 16.1 million. Gartner has PC shipments falling 6.1 percent, also to 16.1 million.

Both firms have Palo Alto-based Hewlett-Packard Co. as the world’s top PC maker: Gartner said HP had nearly 18 percent of the market in the first quarter, while IDC pegs it at almost 19 percent.

But Gartner puts Taiwan’s Acer Inc. in the No. 2 spot, with almost 13 percent of the market and Round Rock, Texas-based Dell Inc. as No. 3, with nearly 12 percent. IDC, meanwhile, has Dell in the second-place spot, with almost 13 percent of the market, and Acer third, with slightly more than 11 percent.

Stateside, they both agree HP and Dell took the No. 1 and No. 2 spots, respectively, but Gartner’s data placed Acer and Japan-based Toshiba Corp. in third and fourth, while IDC’s data showed Toshiba in third and Apple, of Cupertino, in fourth.

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