Apple was one of the few PC vendors in the US to ship more units in Q4 2010 than it did in Q4 2009, according to data released this week.

Preliminary figures from Gartner for 2010 showed that Apple's share of the US PC market grew from 7.4 to 9.7 percent, putting it in fifth place overall.

Of the companies with a greater share of the market, only Toshiba shifted more units in Q4 2010 than it did in Q4 2009. Acer made 2,120,853 shipments in Q4 2010, down from 3,048,552 in the same period for the previous year.

HP and Dell were number one and two in the market, with both posting negative growth of -6.0 and -6.1 percent respectively.

The figures included sales of all desktop and laptop PCs, though not tablet devices such as the iPad or Dell Streak. However, Gartner admitted that such devices did have an impact on the figures.

"Media tablets undoubtedly intensified the competition in the consumer market. These devices do not replace primary PCs, but they are viewed as good enough devices for these who want to have a second and third connected device for content consumption usage. Mini-notebook shipments were hit the most by the success of media tablets," said Mikako Kitagawa, principal analyst at Gartner.

Meanwhile, figures released by rival analyst firm IDC were largely in line with Gartner's with Apple the number five vendor, though according to IDC's calculations Apple only took an 8.7 percent share of the US PC market in Q4 2010, up from 7.2 percent.

IDC did agree that the iPad in particular and the tablet sector in general were having an impact on US PC sales, though. "Growth steadily slowed throughout 2010 as weakening demand and competition from the Apple iPad constrained PC shipments," said David Daoud, research director, US Quarterly PC Tracker and Personal Computing at IDC.

"In addition to relatively high market penetration and a 'good-enough' computing experience with existing PCs, consumers are being more cautious with their purchases and competing devices have been vying for consumer dollars. This situation is likely to persist in 2011, if not worsen, as a wave of Media Tablets could put a dent in the traditional PC market," he continued.