Microsoft chairman Bill Gates has told WinHec conference that his company's Vista operating system was selling much better than expected.

In what will be his last keynote at the WinHEC conference before he retires, Gates said that Vista operating system has been adopted twice as fast as Windows XP.

He said that as of last week more than 40 million copies of the operating system had been sold.

However it is unclear if Vista coupons were counted in the figure which would certianly inflate the figure.  As would counting OEM contracts which will be for copies of the OS for machines that have not been built yet.

More here .