The first public trial, or beta, version of Windows 7 has been released.
Microsoft boss Steve Ballmer used his keynote speech at CES to announce that software developers would get at the trial version on 7 January.
On 9 January members of the public will get the chance to download the successor to Windows for themselves.
Mr Ballmer said Windows 7 would be the pivot of a broader Microsoft push to improve the way its separate software and service families work together.
In delivering the opening keynote, Mr Ballmer has taken over from Bill Gates - who in 2008 bowed out of day-to-day involvement with the company he founded.
In a nod to the chilly economic climate, Mr Ballmer said: "We face some really big challenges. We are all feeling it and its impact will likely be with us for some time."
But, he said, the global economic slowdown would not hobble the pace of technological change.
"I believe our digital lives will only continue to get richer," said Mr Ballmer. "There's no turning back from the connected world."
The newest version of the Windows operating system would, he said, be the "linchpin" of an effort to make it easier for customers to do more with the different Microsoft gadgets and services they use.
Although Windows 7 was a trial version it was, said Mr Ballmer, almost "feature complete" and would help to re-define the way people thought of the software.
Instead of it being an operating system mainly associated with a PC, he said, Windows was becoming a "connected platform and experience".
Microsoft is expected to cap the number of copies of the beta version of Windows 7 available to the public. The minimum requirements for running Windows 7 are a PC with a 1 Ghz processor, 1GB of RAM, 16 GB of disk space, 128MB of video memory and support for DX9 graphics.
Some of the Windows 7's features help it work with other devices. A "home group" system makes it straightforward to enrol PCs, Xbox consoles, media servers and other gadgets into a local network that can share media and content.
Demonstrations during Mr Ballmer's keynote also showed changes to Windows Live online services that let it act as a co-ordinating centre for many of the things people do on the web.In connection with this Mr Ballmer announced a deal with Facebook which would mean any changes a member made to their page on the social networking site would be echoed on their Windows Live pages.