PCs shipments were down 4.9%% globally in Q4 to 90.3 million units because of "must-have" tablets and the dicey state of the world's economy Gartner said.

The researcher figures "Tablets have dramatically changed the device landscape for PCs, not so much by ‘cannibalizing' PC sales, but by causing PC users to shift consumption to tablets rather than replacing older PCs. 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."

"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."

"On the positive side for vendors," it said, "the disenfranchised PCs are those with lighter configurations, which mean that we should see an increase in PC average selling prices (ASPs) as users replace machines used for richer applications, rather than for consumption."

Anyway, HP is back to being number one after losing the prized slot to Lenovo in Q3. Gartner figures HP probably traded profit margin for market share. HP is also stronger than Lenovo in the consumer market, which counts during the holidays.

HP controlled 16.2% of the market last quarter, a pyrrhic victory scored on the back of flat shipments of 14.6 million units while Lenovo, now number two at 15.5%, increased its shipments 8.2% to 13.9 million units.

Dell's market share dropped two points to 10.2% on shipments that plummeted 20.9% to 9.2 million.

US shipments fell 2.1% to 17.5 million units in the quarter and EMEA shipments were down 9.6% to 28.1 million units.

Microsoft's new Windows 8 operating system, released at the tail end of October, had no positive impact on PC market in Q4, a fact Gartner blamed on "lackluster form factors" from the PC vendors and a general "lack of excitement" compared to tablets and smartphones.

In 2012 as a whole PC shipments dropped 3.5% year-over-year to 352.7 million units. HP took 16% on shipments down 6.7%; Lenovo took 14.8% on shipments up 14.2%. Dell shipments were down 12.3% for a 10.7% market share, down a point. Asus was up a point or so to 6.9% market share after its shipments surged 17% to 24.2 million units.