Jean Philippe Courtois, president of Microsoft Europe, described the company as an underdog in Paris today.
He said Bing had between three and five percent market share in search and could only grow - although he admitted it could take a long time.
"We are the tiny guy, and the only way to go is up," he said. "It is a reason why we have made a number of key investments in search and have continued to hire over the last 18 months some of the best people in the industry.
"We do expect to keep investing in learning and investing in getting share year after year - it's going to be a long journey."
And Courtois also reacted with irritation to the suggestion that it had missed the boat with social networking.
Questioned by Etre founder Alex Vieux, Courtois said that Microsoft had been an innovator in the social networking market with Messenger, which had half a billion users.
"The first social network in this country is Messenger, and Messenger has extended services, so it can work with other networks too and it's used by a very large number of people, professionals as well," he said. "There's other forums and communities out there."
Courtois said that sales of PC systems had "fallen off a cliff", dropping by between 10 and 15 percent - and that had inevitably affected Microsoft. He said that he regularly talked to industrial giants in every sector and all were saying that they had to watch their costs. He said that customers were actively measuring the costs of their software infrastructure.
Despite Microsoft having to live with open source software for 10 years, it had retained its share in the market place, he said.