To be fair: rcentros is most likely comparing a recent Linux distribution to XP, a modern OS to an older OS with a multitude of patches. This is a valid comparison if someone is using older hardware that recent versions of Windows don't support. In the context of XP, the only thing that comes off as "zealot-like" in rcentros' comment is the emphasis on the registry.

That depends upon how you measure superiority and are willing to grant that they are equals for many non-enthusiasts.

To give you an idea of what I mean, consider older hardware. You have some people using old machines because upgrading their computer is not a priority and other people are using old machines because they cannot afford to upgrade. If these people are taking their computer online, they should be keeping their software up-to-date. For them, that means spending money and taking time to install Windows. It likely means spending money and taking time to get new hardware. Linux solves most of those problems. The only one it doesn't solve is spending time to install the OS, yet it does meet the user half way by installing a respectable suite of software at the same time.

Along the same lines, you have software installation and updates being better for pretty much all users. This may sound like the domain of the computer enthusiast, and to a large degree that is the point. If you're using the computer as a tool, you probably don't want to worry about that stuff. Now Apple has addressed that through their app store. I suppose Microsoft has done the same with their app store. Yet, on both platforms, the true diversity of software is installed through packages downloaded from third parties. On Linux, it is the opposite. (I will grant you that installing Linux applications from third party sources is usually an order of magnitude harder than it is for OS X or Windows.) The benefits of Linux are a centralized source for most software, a consistent installation method, a uniform update mechanism, a more robust update mechanism, and minimal interaction for all of the above. I'm sorry to be harping on the software update bit, but it is important when your computer is on a public network.

For some users, cost is going to be a factor too. If you can afford commercial software, fantastic! In many cases you will be able to get something that exceeds the capabilities of open source software. In many cases you will be able to get better (or at least more consistent) support. While it is true that most open source software is available for Windows, either formally or through platforms like Cygwin, Linux makes it easier to discover such software. While there is a much wider range of free software for Windows, there is also a question of the motivations behind its development. Open source software is motivated by community development. Close source software developed by hobbyists is developed out of interest. But what is the motivation behind the other free software out there? Sometimes it is clear, such as Amazon making its money through book sales or Adobe making its money through content creation tools. In other cases, it is not clear in the slightest. I suspect that the failure to ask about motivation is why some Windows users are prone to downloading malware while others are not.

It is easy to classify the above as being the domain of the computer enthusiast, and yes it will have a greater impact upon that segment of the market. Yet all of the above also has a huge impact upon people who use the computer as a tool, and who go even a little bit beyond using the software shipped with their computer. Simply put, it pushes foreground concerns (that are usually ignored) into the background for those users.

Of course, there is also a cost to using Linux. The small marketshare and open source tunnel vision means that is going to be a dearth of software in particular areas. Clearly ereading software that supports DRM is one of those areas. The same can be said for tools targeted at professionals (outside of the sciences and engineering). Yet that really ought to be left to individual users to decide, rather than self-anointed.