Over the same period, the introduction of disruptive technologies will create additional risk for PC vendors, by presenting them with technology investment decisions that they cannot afford to get wrong.

In particular, the arrival of hardware support for PC virtualization will challenge the established relationship between PC hardware and software, placing PC vendors in the middle of a tussle for control of platform development between key component suppliers.

Analysts predict that annual PC shipment growth will average eight percent between 2006 and 2009, but revenues will remain flat, leaving many vendors to struggle for survival. Emerging market growth and mobile PC adoption will be the key unit growth drivers over the period.

The formerly safe profits in mobile computing are under attack as plentiful component supplies enable a price-driven market expansion.

"The growing gap between realistic levels of profitability and shareholder expectations will intensify pressure on PC vendors registered in the USA, Japan and Europe, opening up the market to emerging market vendors which have lower labor costs and/or more modest margin objectives," says Brian Gammage, vice-president at Gartner.