I didn't bother reading all nine pages of this post, but if you're still looking for a solid OS Ubuntu, or one of its derivatives, is a very secure choice. Particularly, I'm referring to Linux Mint. Linux Mint is, basically, about 97% Ubuntu, with the last 3% being that they go ahead and include support for a bunch of propriety codecs and whatnot. Basically what this means is that you get the community support of ubuntu without having to do any tinkering to listen to mp3s and watch DVDs etc...
As far as Windows vs. Linux for virus protection, its my understanding that the main security in Linux comes from the fact that about 80% of the market (or greater, I cannot really recall the exact statistic) runs Windows. That being the case, whoever writes a virus would not benefit from writing it for Linux or Mac: they would get the most return on their investment by writing it for Linux.
That is not to say that Linux is not more secure than windows, though. My understanding is that, due to the way that Linux evolved, it is innately more secure than Windows. What I mean by this is that Linux was born and grew over the internet, which is the primary source of threats. That being the case, as it grew, it grew with the proper security necessary to keep it running in an environment which was connected globally over the internet. Windows, on the otherhand, was initially written for personal, local network use. Once the internet started taking off, they realized that they had some huge security flaws, and instead of fixing those flaws (which I'm pretty sure would have meant completly overhauling their code, which is not really feasible) they implemented severall security measures, i.e. Anti-virus software etc..
So, to wrap up, Linux IS more secure than Windows for a couple of different reasons, and, in my experience, it also handles resources (i.e RAM) more efficiently. These are the main reasons I switched to Linux a few years back and haven't looked back. Yea, its kind of a pain sometimes getting one or two things to work, but the payoff is worth it in my eyes.