The next two years will see an unprecedented change in the way television affects people's lives as services honed on the internet and mobile phone move onto consumer's long-time favourite gadget.

This was the view outlined by Microsoft CEO Steve Ballmer, speaking at the Consumer Electronics Show in Las Vegas.

Mr Ballmer said that despite the recession, consumers would look to electronic devices and services to provide more information and entertainment with greater ease of use, and that our favourite gadgets would start to share information.

"It feels like we've entered an age of lowered expectations but digital lives will only continue to become richer. There's so much opportunity, especially in the convergence of the three screens we use all the time: TV, PCs and mobile phones.

"More than a billion people have used a PC, but that means there are five billion who have never accessed one. Netbooks and cheap PC schemes will help the second billion experience computing."

He said that many mobile phones were now almost the match of PCs, with over a billion sold each year. But one screen is due for a technology makeover, he believes.

"The last screen is the oldest but is the least evolved. For 60 years the TV has been the centre of home entertainment but in the next two years the boundary between TV and PCs will dissolve."

TV manufacturers including Toshiba, Panasonic and LG used CES to announce partnerships with internet companies to provide information to a new wave of wireless-enabled televisions, giving consumers the ability to access the rich seam of information and entertainment online without a computer.

Movie and TV programme on-demand services were also heralded as partners of TV builders, including Netflix and Amazon on Demand.

Mr Ballmer insisted that devices and services needed a common platform to ensure that consumers had a seamless and fuss-free experience.

"I believe the linchpin to all of this should be Windows. Nothing matches its power and it is the language spoken by a billion computer users."

Mr Ballmer announced the the full public beta version of Windows 7, the successor to the disappointing Vista scheduled for release in late 2009, woould be available from 11 January from the company's website.

Windows 7 would provide more natural ways for consumers to interact with computers, phones and TVs, he said.

"Windows will be able to see and hear you. Speech and gesture will become important and natural input methods, although the mouse and keyboard will still be used when it is sensible to do so.

Microsoft also announced that Facebook users would be able to get access to updates via Windows Live, giving them the means to manage a range of social networking, news and email services from a single page.