I'm a huge Linux/Open source software fan, for a few reasons. I don't know how to code, nor do I have any knowledge of network security. Even though I've been using Linux for a couple years, I still have only a basic knowledge of the inner workings, i.e. command line tools and the like. However, the philosophy behind open source is right up my alley, so to speak. I'm a firm believer that technology shouldn't be held back by large corporations whose first and foremost motive is profit. With that said, if you use Linux, feel free to post your favorite distro, why you like it, or any other open source software you find helpful.
Personally, I use openSUSE. In my own experience, openSUSE does KDE extremely well. I find YaST to be one of the best administrative tools/graphical package managers out there. It also seems to have excellent tools for network security/administration, though I've never had a need to make use of those them. The Packman repositories are another great resource. There's just so much software! Only issues I ever seem to have, with any distro, is my graphics card apparently hates compositing, especially compiz. It plays ok with kwin, but sometimes still crashes. I may end up switching to the nouveau driver, because it seems more stable than the official nvidia drivers.
I've used Fedora, Ubuntu, Linux Mint (Ubuntu base) in the past, and I've played around with other distros in Virtualbox, usually when I'm bored. If you haven't tried Linux Mint, I highly recommend it over its Ubuntu base. Totally community supported, and it managed to work it's way up to number 3 or 4 on DistroWatch, I think.
Feel free to post links and/or screenshots.