Fresh from an overnight flight to London after launching the product in New York's Times Square, Gates traced the development of Windows from its origins in the mid-1980s.
"In Windows Vista, we have the foundation to take things to a whole new level," he said, adding: "We worked hard to build a new software platform, and we're so excited to see what people are going to do with it.
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Hailing the new product as revolutionary, he cited notably how it would change "the way people buy and sell products, the way we think of telephony (and) the revolution of television."
"We're just at the very beginning of that. We've just begun to see what we can do," he added.
The new operating system, which replaces Windows XP, notably has new graphics capabilities, more rigourous security and far more powerful ability to handle games, music and videos.
After a glitzy launch party in New York on Monday night, it went on sale from midnight on Tuesday in 70 countries around the world.
Retailers a