Worldwide shipments of personal computers fell in the second quarter as an increasing number of consumers opted for tablets instead of PCs, while others held off buying until new products hit the market later this year.

Worldwide PC shipments fell .1% during the period, while shipments in the U.S. slumped 10.6%, according to market watcher IDC. One reason for the decline: buyers are waiting for Windows 8 products from Microsoft and its partners.

"The announcement of a Windows 8 launch date, as well as broader communication of new features in the OS, are key steps that would help to address uncertainty about new product availability and help consumers and channels plan their purchases," said IDC analyst Jay Chou.

Microsoft this week announced that Windows 8 systems would hit the market in October, but the company did not provide a specific date. In an effort to maintain pre-launch PC sales, Microsoft is offering a deal through which consumers who purchase a new Windows 7 PC can upgrade later to Windows 8 for just $14.99. The offer is valid through Jan. 31. PC users with older systems can upgrade for $39.99.

[ Considering a Windows 8 ARM tablet? Here's what you need to know now: Windows 8 ARM Tablets: 8 Must-Know Facts. ]

Still, Chou said he believes Windows 8's arrival will jumpstart PC sales, but not until later in the year. "We don't expect PCs using Windows 8 to boost growth significantly until the fourth quarter, which leads to a conservative outlook for the third quarter," said Chou.

Adding to the slump was the fact that consumers are embracing tablets, specifically Apple's iPad. While Q2 PC shipments slumped, Apple said it sold 11.8 million iPads during the second quarter, an increase of 151% compared to the same period a year ago.

Hewlett-Packard led all PC makers in worldwide shipments in Q2, grabbing 15.5% of the market. Lenovo was second, with 14.9%, while Dell held an 11.1% stake. Acer and ASUS took 10.4% and 7.1%, respectively, according to IDC.

HP also led the U.S. market, with a 25.9% share, followed by Dell (22.5%), Apple (11.4%, not including iPads), and Lenovo (8%).

"These latest results validate IDC's expectations that the second quarter would be a transition period where both economic factors and anticipation for new products in the second half of the year would result in relatively low PC shipment growth," said Chou.

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