Microsoft plans to include touch screen functionality as a feature of the operating system in the next version of Windows, code-named Longhorn.

Support for touch screens will come in addition to support for pen-based input that Microsoft currently offers in Windows XP Tablet PC Edition.

Microsoft hopes the support in the operating system will move PC vendors to add touch screens to their mobile PCs, especially Tablet PCs.

"We believe that the dual-mode input option on [Tablet PCs] will appeal to users," a spokesperson says.

On stage at the Windows Hardware Engineering Conference (WinHEC) in San Fransisco this week, Microsoft demonstrated a Fujitsu Tablet PC running Longhorn with added touch screen support.

Microsoft is working with component manufacturers to lower the cost of the required hardware so PC makers will seriously consider adding touch screens to their Tablet PCs.

"If you can have dual-mode input for a comparable price, why not do both?" the spokesperson says.

Longhorn is due out late next year. Microsoft has not yet disclosed packaging plans for the operating system.

The touch screen support may be limited to a Tablet PC version of the operating system, if such a special edition is released, but could also be part of all editions of Longhorn, according to Microsoft representatives.