Actually, cost is not what makes the sale for Linux. It's the portability of the operating system, the fact that you can build your business on Linux and can change hardware vendors or architectures. For corporate customers, you need to provide a highly reliable platform, and they prefer to have a choice. So with Linux, they have a choice of vendors or a choice of architectures, and they're not buying into a single corporation or a single solution. Microsoft's Jim Allchin recently had some harsh words, suggesting it stifles innovation.
Open source is good for business.
Now I should add that open source is not for everything in software. We have a very large and successful software business, and we're going to retain that. But open source is great for infrastructure code. The reason is that to make open source work, there has to be an overlap between the people who care about the software and the people who make the software better. The world spends way too much time and energy doing exactly the same thing in a proprietary fashion.