Netbooks were instrumental in the increase in PC shipments for most manufacturers during the third quarter, but Apple defied the trend despite offering standard laptops at premium prices, according to figures from analyst firm Gartner.

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Apple executives in the past have trashed netbooks as junky devices with cramped keyboards and the company does not yet have a netbook on the market. Most PC vendors, including Acer, Hewlett-Packard and Dell are offering netbooks, which are low cost and designed to perform basic tasks like word processing.

Apple's PC shipments in the U.S. grew year-over-year by 6.8 percent to total 1.57 million during the third quarter, placing the company fourth behind Dell, Hewlett-Packard and Acer, according to numbers released by Gartner on Wednesday. Overall PC shipments in the U.S. grew by 3.5 percent year-over-year to total 17.82 million.

Apple's growth was driven by dedicated fans of the company's products and the education market, said Mikako Kitagawa, principal research analyst at Gartner.

Comparatively, growth in PC shipments for companies like HP and Acer came from low-priced laptops and mini-notebooks, which includes netbooks. Netbooks especially helped Acer's shipments, which grew by 61.4 percent year-over-year. HP's third-quarter shipments grew by 2.7 percent.

Netbooks attracted interest during the quarter because of low prices, Kitagawa said. Dell offers netbooks, but its shipments dropped by 8.9 percent during the quarter, Gartner said.

Like Apple, Dell is trying to de-emphasize netbooks to focus on profit margins, but there is a difference between the companies, Katagawa said. Dell offers mini-notebooks, but isn't as aggressive in the space as Acer and HP. Dell was the top PC vendor in the U.S. with a 26.2 percent market share, while Apple held an 8.8 percent market share.

Apple's brand recognition means that its customers do not mind paying a premium, she said. "That is what they are built for, that is something no other PC vendor can do," Kitagawa said.

Dell has especially struggled to build strong brand recognition, with issues surrounding customer support and product returns affecting the company's reputation.

There is also a big installed base of Apple systems in the education market and those buyers tend to stick with Apple PCs. Dell has made an aggressive play in the education market in recent years, launching new products designed for use in schools and classrooms, and offering discounts.

"Switching to Windows is too expensive for that audience," Kitagawa said.