People are buying tablets to replace old PCs, which explains why PC sales were so dismal over the holidays, according to Gartner.

Small, portable, capable, inexpensive, touchscreen tablets grab sales from low-end PCs and mean that old PCs will not be replaced with new ones, says Mikako Kitagawa, a Gartner principal analyst, and that is a significant change in how PC sales work.

"Whereas as once we imagined a world in which individual users would have both a PC and a tablet as personal devices, we increasingly suspect that most individuals will shift consumption activity to a personal tablet, and perform creative and administrative tasks on a shared PC," Kitagawa says.

"This transformation was triggered by the availability of compelling low-cost tablets in 2012, and will continue until the installed base of PCs declines to accommodate tablets as the primary consumption device."

That is the battle Windows 8 is fighting, Gartner says, although the scarcity of Windows 8 touch devices may so far have hampered sales. With new touch machines being promised for later this year, that may help Windows 8 grab a larger share of PC sales but not help the overall number of PCs sold, Gartner says.

Sales were down 4.9% in Q4 2012 vs. Q4 2011, Gartner says, which goes along with IDC numbers from last week, although IDC's number, 6.4%, is larger. "During the holiday season, consumers no longer viewed PCs as the number one gift item," Gartner says in a press release.

PC purchases by businesses went against the general trend, Kitagawa says, which is typical because businesses often make year-end purchases for tax reasons. "Our early research indicates that there was good growth in professional PC sales," Kitagawa says.

The upside for PC vendors is that as customers walk away from low-end models sales of high-end devices will persist, giving vendors a higher average selling price, Kitagawa says.

Tim Greene covers Microsoft for Network World and writes the Mostly Microsoft blog. Reach him at [email protected] and follow him on Twitter @Tim_Greene.

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