Bill Gates probably will not sing the praises of Keith Curtis, a programmer with Microsoft for 11 years who's now left the fold and written a book about why the Redmond way will fail. Oh yeah, Curtis is not afraid to speak his mind as a Linux guru, either.

The mantra Curtis repeats throughout his book "After the Software Wars": proprietary software is holding us back as a society.

In the book, Curtis says that while proprietary software made Microsoft one of the most successful companies of all time, it's a model destined to fail because it doesn't let software programmers cooperate and contribute, and thus stifles innovation.

Curtis did programming work on Windows, Office and research at Microsoft and never actually used Linux, he says, until he quit his job in late 2004. The ensuing years have made him a Linux fanatic, and he is convinced that free, open-source software is technically superior. As long as Microsoft and its proprietary model dominate, Curtis says, we will live in "the dark ages of computing."

In an interview with CIO.com's Shane O'Neill, Curtis discusses the rise of free software, Linux's role in what he calls the inevitable fall of software's biggest giant and ... robot-driven cars.

In what ways will free software be Microsoft's undoing?

Free software will lead to the demise of Microsoft as we know it in two ways.

First, the free software community is producing technically superior products through an open, collaborative development model. People think of Wikipedia as an encyclopedia, and not primarily software, but it is an excellent case study of this coming revolution.

There are also many pieces of free software that have demonstrated technical superiority to their proprietary counterparts. Firefox is widely regarded by Web developers as superior to Internet Explorer. The Linux kernel runs everything from cellphones to supercomputers. Even Apple threw away their proprietary kernel and replaced it with a free one.

Second, free software undermines Microsoft's profit margins. Even if Microsoft were to adopt Linux — a thought experiment I consider in the afterword of my book — their current business model would be threatened. There are many ways for hardware and service companies to make money using free software, but these are not Microsoft's sources of revenues.

Free products like Linux and Google Docs currently comprise only a tiny proportion of their respective markets compared to Microsoft. What will it take for free software to truly catch on with consumers and businesses as you predict it will? And how long will that take?