Worldwide Sales of personal computers are expected reach 364 million units in 2011, up 3.8 percent from 2010 according to an updated forecast from the Gartner research firm. While the numbers are expected to be positive for the year, the estimates are much weaker than originally predicted.

This report marks the third time this year that Gartner has lowered it PC sales predictions. At the beginning of this year, the research firm was predicting sales of personal computers would grow 15.9 percent in 2011. That number was reduced to 10.5 percent in March, 9.3 percent in June and now 3.8 percent.

The firm has also lowered its forecasts on next years sales of laptop, netbook and PC sales. Gartner now predicts 10.9 percent more PCs will be sold in 2012 than in 2011. Actual PC sales in 2009 in 2010 were 308 million and 350 million units respectively. Estimated sales for 2011 and 2012 now stand at 364 million and 400 million units respectively.

Gartner says the revision downward is due to sharply downgraded forecasts for Western Europe and the United States in the second half of the year.

"Western Europe is not only struggling through excess PC inventory, but economic upheaval as well," said Ranjit Atwal, research director at Gartner. "U.S. consumer PC shipments were much weaker than expected in the second quarter, and indications are that back-to-school PC sales are disappointing."

In addition to economic woes, the rapid growth of tablet computers.

"Media tablets have dramatically changed the dynamic of the PC market and HP's decision to rethink its PC strategy simply highlights the pressure that PC vendors are under to adapt to the new dynamic or abandon the market," said George Shiffler, research director at Gartner.

Gartner's PC forecasts do not include the fast growing tablet computer category. In April, Gartner predicted global sales of 70 million tablets in 2011, up fourfold from 17.6 million in 2010.

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