Overall PC shipments reached 67.2 million during the period, a fall of 6.5 per cent against the same period last year, and the situation may get worse, the analyst firm warned.
"We are seeing some evidence of channel inventory restocking, particularly in the US," said George Shiffler, research director at Gartner. "This restocking should not be interpreted as a recovery in PC end-user demand. It is still unclear if the global PC market has hit the bottom."
HP shipped almost 20 per cent of all PCs sold, and displayed stronger than average growth rates in the US, Asia Pacific and EMEA. HP's gain is significant, as it is the first time since 2001 that the firm has shipped more units that Dell.
Gartner placed much of HP's success on its "solid consumer PC portfolio, including low priced mobile PCs".
"Low priced mobile PCs continued to be the growth driver for the PC industry in most regions," said Mikako Kitagawa, principal analyst at Gartner. "However, we anticipate a sharp decline in industry revenues due to the lower average selling prices of these devices."
PC shipments in Europe fell to just below 23 million, representing an alarming 10 per cent fall.
"The EMEA PC market in the first quarter of 2009 suffered its worst decline since 2001, showing a drop in double digits," said Ranjit Atwal, principal analyst for Gartner's client computing markets group in EMEA.
"The market also experienced a 25 per cent decline quarter-over-quarter as a result of further reductions in channel inventory and lower levels of demand."
HP once again dominated, registering over 21 per cent of all sales in EMEA. Acer, which beat Dell to second place, shipped just under 20 per cent.
Gartner identified the UK as the worst performing market in EMEA.
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