For the second time in a row HP beat out Dell in moving PCs worldwide, this time increasing its lead, according to both Gartner and IDC.

Gartner reckons HP shipments in Q4 grew 24% in Q4, giving it 17.4% of the world market, and it figures Dell's sales dropped 8.7%, reducing its share to 13.9% from 16.4% year-over-year.

IDC gives HP 18.1% to Dell's 14.7%.

In Q3 HP had 16.3% and Dell 16.1%, according to Gartner.

Number one since 2003, Dell lost the premier position this past Q3 in a turnabout fraught with implications and dire foreboding for the struggling Texas giant. The Q4 numbers are Dell's worst showing in years.

Dell, which is juggling profitability versus share protection, remains the leader in the US where it held 31% of the market to HP's 22%, according to IDC, but Dell lost share across-the-board there too and its US shipments were down 17.3%, according to Gartner, which gives Dell 29.1%, down from 34% year-over-year, and HP 25.3%.

The US market contracted around 3% in Q4 and HP is stronger than Dell offshore. Business wasn't buying and there is some speculation that Vista's delayed availability might be a factor in America's sluggishness or maybe people put their money in flat-panel TVs and iPods instead. Apple also gained share, increasing its shipments 30.6% to carve off 5.1% of the market, Gartner says. IDC gives Apple 4.7% of the US market, with shipments up 31.8%, and 2.4% of the world market.

Worldwide PC sales were up either 7.4% (Gartner) or 8.7% (IDC) in Q4. For the year they were up around 9% to roughly 230 million units with Dell and HP pretty much tying at 16% or 17% followed by Lenovo, Acer and Toshiba in that order.

Gartner is currently predicting PC shipment will grow 9.9% this year but total revenue will be a flat $201 billion.