Market tracking firm IDC said that in the third quarter of 2008 notebooks accounted for over 50% of personal computers shipped in the U.S. for the first time in history of the industry. The share of notebooks shipped in the USA in Q3 2008 stood at a solid 55.2%, according to preliminary figures from IDC’s U.S. quarterly PC tracker. It is important that both consumers and businesses preferred notebooks to desktops.

“The consumer market continued to be the top driving factor in the notebook offensive but the commercial sector played a critical role too,” said David Daoud, research manager of U.S. quarterly PC tracker and personal systems at IDC.

The 55% ratio was made possible by a record volume of notebooks shipped in the third quarter of this year – over 9.5 million units – representing more than 18% growth both year-over-year and on a sequential basis, according to IDC’s preliminary data. These figures were reached amid a relatively active back-to-school season and the burgeoning financial crisis, which captured headlines, but did not immediately affect the PC market’s performance.

Almost all the leading vendors with desktop and notebook offerings shipped greater notebook volumes in the quarter. Some vendors, such as Toshiba, have long focused exclusively on notebooks. Others, including Sony, Acer, and Lenovo exceeded the 65% notebook ratio within their own PC client shipment base. Attracted by the opportunities of an expanded multi-PC-per user base, new notebook-focused vendors are making their way into the U.S. market, including Asus and Samsung, which primarily target consumers with their devices. The potentially expanding mid-tier vendor base is likely to further increase competition among well-known brands, with the potential for lower prices to stimulate demand and keep unit growth in positive territory.

“The consumer market has long favored notebooks, with mobile ratios exceeding the 70% mark. So it is clear that the small and mid-markets, as well as the enterprise and public sector buyers, are seeing good value in mobility. Looking ahead, while mobility will remain a leading growth factor, the economy will be a major wild card in the short to mid term. Prolonged economic tension could have an adverse effect on the PC space leading to reduced growth, but the good news is that virtually every buyer considers PCs as must-have products and not a secondary wish-list items,” added Mr. Daoud.

IDC’s U.S. quarterly PC tracker gathers PC market data in the United States by vendor, form factor, brand, processor brand and speed, sales channel and user segment. The research includes historical and forecast trend analysis as well as price band and installed base data.