By Slash Lane

Published: 02:00 PM EST (11:00 AM PST)

If the iPad is categorized as equivalent to a traditional laptop, Apple is the largest mobile PC seller in the U.S., and the third-largest worldwide.

DisplaySearch on Tuesday revealed its Quarterly Mobile PC Shipment and Forecast Report, in which it noted that the "iPad effect" is shaking up the mobile computing market. In less than a year on the market, the iPad already represents 8 percent of global shipments of all mobile PCs.

Globally, the research firm found that HP led in unit shipments of mobile computers in the third calendar quarter of 2010, with 9.5 million. Acer was close behind in second with 9.1 million.

Apple's 6.3 million mobile devices shipped in the third quarter was good for third place, with a 12.4 percent share. But without the iPad, DisplaySearch said Apple would have come in eighth place with 4.8 percent of the mobile PC market.

"A lack of competitive tablet PC products from other brands continues to drive Apple's market share in the mobile PC segment," said Chris Connery, vice president of large format displays at DisplaySearch.

But the firm noted that Apple faces challenges with the international expansion of the iPad, citing Japan where iPad adoption was categorized as "weak." The NPD Group research company said that Apple must overcome the "Western-centric nature" of the iPad and support the local needs of nations overseas.

"On a global scale, the adoption of iPad is not without its challenges," said Hidetoshi Himuro, director of IT market research at DisplaySearch. "Localized content in non-English speaking regions is sparse, and iPad owners must have a PC for downloading content from iTunes. As a result, penetration in developing regions will be slow."



In October, analyst Chris Whitmore of Deutsche Bank recognized that including the iPad in PC unit sales would make Apple the largest seller of computers in the U.S. With the Mac alone, Apple had more than 10 percent of domestic PC sales last quarter.

In its quarterly earnings report in October, Apple revealed that it shipped a total of 4.19 million iPads in the final quarter of its fiscal year 2010. Mac shipments, including desktops and portable devices, were a record 3.89 million worldwide.

Though the iPad is already outselling the Mac, reports have suggested the "cannibalization" effect of Apple's touchscreen tablet on Mac sales has been minimal. Still, tablets like the iPad are projected to have a significant impact on the PC market as a whole, with Gartner projecting that tablets will "displace" 10 percent of PC sales by 2014.

Others, however, expect the tablet disruption to come even sooner -- next year. Craig Berger of FBR Capital Markets predicted that every 2.5 tablets sold results in a lost PC sale. He sees Apple selling 40 million iPads next year, and competing tablets achieving 30 million total sales, displacing 28 million conventional PCs.