Eric Schmidt is not Bill Gates. The cerebral computer scientist at the head of Google is far more affable than the intense, fiercely driven college drop-out who turned Microsoft into the world's most powerful technology company.

For the past two decades, Mr Schmidt, 54, has pursued a vision for computing very different from Mr Gates. In fact, his career has been defined almost in opposition to that of the Microsoft co-founder. This week, as Google disclosed that it would release a PC operating system to rival Microsoft's Windows, those two worlds collided.