Tablets are taking a big bite out of PC growth.

Reports from two research firms, IDC and Gartner, showed a drastic slowdown from last year. In the fourth quarter, Gartner said PC shipments grew 3.1 percent over the same quarter in 2009, while IDC said sales grew 2.7 percent. For the calendar year, the figures were 13.8 and 13.6 percent, respectively.

Reasons given for the shrunken growth for PC shipments include a softening demand in the Asian markets (excluding Japan) and the U.S. But the real culprit, according to the analysts, was the increased competition from media tablets, such as the Apple iPad.

Growth steadily slowed throughout 2010 as weakening demand and competition from the Apple iPad constrained PC shipments, said David Daoud, research director at IDC, in a statement.

Overall, holiday PC sales were weak in many key regions due to the intensifying competition in consumer spending. Media tablets, such as the iPad, as well as other consumer electronic (CE) devices, such as game consoles, all competed against PCs, said Mikako Kitagawa, principal analyst at Gartner.

The increased amount of tablet shipments meant bad news for mini notebook PCs. Dell, Lenovo and Toshiba increased their shipments, while Hewlett-Packard and Acer did not. According to IDC, HP suffered slowed sales of mini notebook PCs and consumer purchases. Acer, whose PC shipments dropped by 15 percent, also suffered from slow sales of mini notebooks.

The companies that increased in shipments did not rely as heavily on the mini notebooks. Dell, Gartner said, benefited from professional PC refreshes across key regions. The situation could get worse in 2011 for PCs, according to Daoud.

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, Daoud said.