...Winodws operating system?

Yes, there are fewer vulnerabilities in Linux systems and security holes are patched faster than Microsoft.

Yes it is, for a few reasons. Linux comes with a built in firewall that is very customizable and much more robust than the Windows firewall. Linux is also more stable since it is all based on Unix code. Perhaps the biggest reason it is more secure though is that most hackers REALLY hate Microsoft. When is the last time you heard of a virus that attacked Linux systems? Hackers use Linux to write viruses that attack Windows.

This question has been more controversial than technical. It depends on your definition of security and how you approach it. Each party claims that its OS is more secure. But generally speaking, the experience showed that Linux has much less viruses/malware that Windows but this can be justified by the low number of users of Linux compared to Windows which as a result doesn't attract virus writers and hackers. For the design of the OS itself, see the sources for more detailed discussion.

blogs.zdnet.com

As everyone else has said, yes. I'm just repeating.BSD is more secure.