You're right, it got way off topic. Just a word of caution, before you go deeply into Linux, make sure the OS is going to be as friendly as Windows for accomplishing the tasks you do most. Like most things, Linux shows preference for some tasks over others. A bit of research will show you what I mean. I think most of us agree on that one. Longhorn???
Therein may lay your problem; never depend on an OS for security. There are top notch software and hardware to accomplish that need. Computer techs will use some combination of second party utilities and/or hardware to protect and clean the systems they're responsible for. Nowadays, different OS are under attack to some extent, so they all need protection.
I wonder how much of the success is due to obscurity. I'll just stick to windows. That's where more of the useful, as well as more advanced entertainment, programming is. You'll have to admit, most of the cutting edge as well as utility programming is directed to the microsoft windows market.
well it is not an OS for desktop but that is one of the server types of OS well.. it's off a bit again ;p