Microsoft's chief operating officer, Robert Herbold, said he wanted the West Coast of America to remain "the centre of the universe for the software business". However, he said he and his colleagues would have to look outside the US for many of the new workers, as good software developers were in short supply in the States.
Mr Herbold said: "Finding enough software developers in the United States is difficult, and we have to be looking outside the country. We already are."
A spokesman for Microsoft said 800 new recruits would replace departing workers, 2,000 would take up posts at the company's suburban Seattle headquarters, and 800 would look after sales, service and marketing around the country.
Mr Herbold said he would identify potential employees in countries such as Ireland, home to the company's European manufacturing and distribution centre, India and China.
However, Mr Herbold did sound a note of caution, saying that in some markets the company had cut staff numbers to improve efficiency. The Dublin manufacturing outfit has shed 92 workers over the past nine months and 47 jobs went from a similar centre in Humacao, Puerto Rico.
Mr Herbold said there were limits to Microsoft's growth in the Seattle area and in Redmond, Washington.
Speaking about Microsoft's interactive media division, which includes high-profile projects such as the Microsoft Network online service, he said it was still an experiment and not yet a business.
"We put down projections when we think it will be making money," he said. "But the one thing about this area that is certain is that uncertainty rules."
He said profits in the emerging business could soar when 50 per cent of the nation's households were hooked up to the Internet, which he said would create an "inflection point". It was possible that point could be reached in 2001, he said.