Keith Curtis worked at Microsoft for 11 years, coding on Windows, Office, and at Microsoft’s research department, before leaving the Redmond giant. Call it a revelation, call it giving in to the devil’s temptations, but he’s now a complete open source and Linux advocate, and in his new book, “After the Software Wars”, he explains why open source will prevail against Microsoft’s proprietary model.

Curtis never actually used Linux until 2004, when he left Microsoft. Over the years, he turned into a Linux advocate, and now claims that thanks to the proprietary software model, we are living in “the dark ages of computing.” This is what is scientifically known as doing a complete 180 (no, not a 360).

In an interview with CIO, he explains why the open source model will ultimately lead to Microsoft’s demise. First, he argues that the open source model leads to better code. He points to Firefox and the Linux kernel as examples of open source delivering greater quality than the proprietary model. Secondly, he also states that open source undermines Microsoft’s profit margins.

He further argues that while open source may not have made tremendous gains just yet in the desktop market, it is doing very well in other segments of the computing market. “Google has hundreds of thousands of machines running Linux,” he explains, “Free software is well on its way to conquering the small and the large, and the remaining challenge is the desktop in the middle.”

It would be hard for Microsoft to adapt to the open source model. Sure, Microsoft could open source its products, but who would care? For instance, if they were to open source Internet Explorer, no one would care because Webkit and Gecko already exist. “If Microsoft, 20 years ago, built Windows in an open way, Linux wouldn’t exist, and millions of programmers would be improving it rather than competing with it,” he says, “However, I think it is too late for that now.”

So, does he believe that there are other ways for Microsoft to compete with open source? “Other than adopting Linux, there is little Microsoft can do,” he starts, “Even if they did embrace it, not only would it hurt their profit margins, they’d be forced to explain to customers why they should continue to pay for Office if the company believes the free OpenOffice is good enough.”

It sure is an interesting view on the debate, especially coming from someone who worked at Microsoft for so long. Personally, I don’t think of open source destroying proprietary – I see open source and proprietary competing with one another, so that we, consumers, end up with better products. Open source made Microsoft improve both its server and desktop offerings on the operating system front, and even when it comes to Office, Microsoft has made tremendous steps forward that wouldn’t have been made without open source breathing down their necks.

At the same time, the continuous comparisons drawn up between proprietary products and their open source counterparts also serve as a carrot for open source developers to work even harder to improve their code and products.

It’s a win-win situation for us consumers, people. And now I want to wash my mouth with soap for saying “win-win situation”.