> If it were impossible to pirate Windows, would all the pirates switch to Linux or another Free OS? If the answer is No, then a non-zero number of people will go out and purchase Windows. From a sales standpoint, preventing piracy is definitely going to drive sales.

What your not counting is the number of people who would be happy to purchase it because it's more convenient but get the pirated version because it's superior, being unencumbered by DRM.

As a firefox or chrome user for instance I could pay for netflix, but the will only deliver the 720p version, why would I pay for a worse product?