Polio's pretty special because once you get an eradication, you no longer have to spend money on it; it's just there as a gift for the rest of time.

But the improvements will happen faster and last longer if we can channel market forces, including innovation that's tailored to the needs of the poorest, to complement what governments and nonprofits do. We need a system that draws in innovators and businesses in a far better way than we do today.

I have to say that in 1981, making those decisions, I felt like I was providing enough freedom for 10 years. That is, a move from 64k to 640k felt like something that would last a great deal of time. Well, it didn't - it took about only 6 years before people started to see that as a real problem.

While we're all very dependent on technology, it doesn't always work.

Depending on how quickly you get ocean rise, you have people who live in river deltas [at risk]. Bangladesh is largely a river delta, and the rising sea level means that when storms come in, the human sanitation is backing up, the ability to farm, it's destructive-type situations like you saw in New Orleans with Katrina. You're increasing the frequency of that stuff in low-lying areas fairly dramatically.

Microsoft's only factory asset is the human imagination.

Money has always been in politics. And I'm not sure you'd want money to be completely out of politics.