Long-term vision and product strategy.

To succeed, you also have to know how to make choices and how to think more broadly.

I went public too soon. Stay private as long as you can.

I really do think cancer will largely be a solved problem. I think most of the infectious diseases like malaria - our foundation is very involved - once we're finishing polio eradication, then starting up this malaria eradication, and getting that done as fast as we can.

The most important 'speed' issue is often not technical but cultural. It's convincing everyone that the company's survival depends on everyone moving as fast as possible.

Going out in the field, it's always enlightening to see what's working and what's not and to sit down and talk - I was with young girls in south Africa - understanding why our tools for prevention aren't being adopted, and what way may need to invent to help protect them.

We're responsible for the creation of the PC industry. The whole idea of compatible machines and lots of software - that's something we brought to computing. And so it's a responsibility for us to make sure that things like security don't get in the way of that dream.