The worldwide PC market is set to experience its sharpest unit decline in history, as more and more customers opt to hold onto their existing kit for longer thanks to the economic downturn.

So says analyst house Gartner, which said that PC shipments will hit 257 million units in 2009, an 11.9 percent drop since last year. The drop will be nearly four times that experienced in 2001, when PC shipments fell by 3.2 percent.

"The PC industry is facing extraordinary conditions as the global economy continues to weaken, users stretch PC lifetimes and PC suppliers grow increasingly cautious," said George Shiffler, research director at Gartner.

Gartner said the fall in shipments would affect both mature and emerging PC markets. Emerging markets collectively recorded their lowest growth in 2002 - 11.1 percent - while mature markets recorded their lowest growth in 2001 - minus 7.9 percent. The research firm said this year emerging markets will post a decline of 10.4 percent, with PC shipments in mature markets declining by 13 percent.

Mini laptops and netbooks represent the only bright spot for suppliers. While desktop PC shipments are predicted to drop by 31.9 percent to 101.4 million, mobile PCs will grow by 9 percent, hitting 155.6 million shipments, said Gartner.

"The mini-notebook market is dividing as vendors offer more systems with 9in to 10in screens in addition to those to with 7in to 8in screens," said Angela McIntyre, research director at Gartner. "For the most part, users are moving toward systems with larger screens and greater capabilities; systems with 8.9in screens were the standard in the second half of 2008.

"Naturally, systems with larger screens and greater capabilities cost more but prices in general continue to fall. Mature markets continue to be the primary consumers of mini-notebooks, but as prices continue to fall, they are likely to attract increasing numbers of emerging market buyers."

"This isn't surprising at all," said Rob Lovell, CEO of ThinkGrid, a provider of hosted IT solutions for businesses. "Part of the decline will be due to the economy; however, the emergence of hosted desktops and software as a service is undoubtedly aiding this trend."

Lovell thinks that rather than having to go through the hassle of refreshing their desktop hardware every two or three years, businesses will hang onto their old PCs and instead use them to access hosted desktops (VDI) and a range of other on-demand IT services.

"Unfortunately, for PC manufacturers, this isn't just a blip but a sign of things to come," he said. "Businesses will turn to hosted desktops and cloud services rather than investing in local hardware and software."