Why I Run Linux

Well, to start with, NO viruses, malware, trojans, or other bad stuff. Linux has had excellent security built in to it from the very beginning. A major difference between a Linux (more properly, a GNU/Linux) platform and a Windows platform is that a Linux platform has a strong implementation of the "Permissions" concept. This strictly divides the "User Space" from the "Administrator Space", meaning a malicious program (a.k.a. "Drive-By Download") will NOT be able to install itself and cause all kinds of grief because it does not have "Permission" to do so. This can sometimes be a PITA if you try install a program as a "User", and the program requires "Root" (a.k.a. "Administrator") permissions. Most programs these days will tell you what they require, and it's a lot better than it was in the old days. There's also methods to put the program in a 'protected' area that will allow it Root privlieges, but keep it from going anywhere it's not supposed to.
I like to 'tinker' with stuff, and since Linux gives you full control over your hardware, you can just about make your PC roll over and bark, if you want. Another advantage is that if you're into programming, or want to learn, most Linux distributions come with all the programming tools you'll need, for free. To buy similar tools for use on a Windows platform would cost hundreds of dollars, or even more for some of the advanced developer's suites out there.
When I first started using Linux back in 1995, there were always problems with hardware support, and some of the early Office type programs were quite, uh, shall we say, 'primitive'? I remember taking about a week to get my modem working correctly, and then another day or two to figure out how to download Netscape, and get it installed. These days with distributions like Ubuntu, it's 95% plug-and-play for your hardware, and the Firefox browser and OpenOffice suite will install automatically.
*SOME* devices, particularly "GDI" printers and scanners, will have hardware that requires the Operating System to do most of the work, and these won't work, or work very poorly, with Linux. When in doubt, use Google to find out if your hardware is Linux compatible.
I won't go much further here, as there are literally thousands of websites devoted not only to Linux in general, but also for all the different distributions out there. If you interested, two excellent books to start with are "Running Linux", and "Linux in a Nutshell", both available at Amazon, Borders, or from the publisher, O'Reilly.