
Gates said at the All Things Digital conference in San Diego in the countdown to his July departure from the company that Windows 7 would embrace new forms of communication and interaction.
"The way you interact with the system will change dramatically," he said. " Today almost all the interaction is keyboard-mouse. Over the years to come, the role of speech, vision, ink - all of those things - will be huge."
In contrast to the heavy pre-launch hype surrounding Vista, Microsoft has so far revealed little about the company's next operating system.
Gates was joined by chief executive Steve Ballmer who described the multi-touch screen demonstration as "just a smallest snippet" of Windows 7.
Ballmer also said he was aiming for Windows 7 "to do better" than Windows Vista.
Ballmer claimed that Microsoft has sold 150 million copies of Vista since its launch in January 2007.