Gartner is currently figuring PC shipments will drop 11.9% this year to 257 million units worldwide, the steepest plunge ever. PCs’ worst showing before was in 2001 when the market declined a mere 3.2%.

Gartner says sales in emerging countries will contract for the first time ever too – by 10.4%, it thinks, versus 13% in developed countries.

It figures desktop sales will be down 31.9% to 101.1 million boxes and laptops up 9% to 155.6 million units.

It thinks netbooks will be up 79% to 21 million units, representing 8% of total PC shipments but a drop in the proverbial bucket.

Gartner research director George Shiffler described how the world will come undone, “Slower GDP growth will generally weaken demand and slow new penetration,” he said, “lengthening PC lifetimes will reduce replacements and supplier caution will keep inventories at historic lows.”

Meanwhile, IDC cut its numbers on PC sales in Asia sans Japan by ~10%, saying that they would be flat this year at 74 million units. It’s less optimistic than it was about next year, taking its Asian growth numbers down 5% to 13% and then up 21% in 2011. We just have to live that long.