The Web According to Ballmer:

Open source is not a new technology area. It was a new business model. In the last three or four years, we have competed very well by extending our value. Open source never goes away as a business model or competitor. We have learned how to compete with open source, and we will compete with it for the rest of time. But competing with open source will have to be something that’s burned bright on the foreheads of our senior people.

The second big competitive force is advertising as a business model. Typically, people just want to reduce that to Google, and if you want to do that, you can. But it’s do we embrace advertising fully enough as a business model? Because at the end of the day, anybody who comes at you with a cheaper-to-the-customer proposition, you got to worry about. And advertising looks cheaper to a consumer than something you pay for. In the case of open source, we couldn’t adopt the business model. We adopted a competitive approach that so far has worked very well. In the advertising case, we can embrace that model. We don’t have to sit here and say it’s that bad.

A third model I could sit here and write down on this list is that there are cases where software gets monetized through hardware. That’s what an iPod is. iPod is a software thing. You just happen to collect the money on the hardware. You could say in China and India, it’s unclear whether classic software will get paid for as much as advertising, hardware, subscriptions, etc.