So I see at least a couple of us are Linux fans.
I'm not an exclusive Linux user, so don't expect me to go on an anti-every-other-OS rant. I regularly use Windows (XP & Vista), Mac 10.3 and Linux; some days I love them all, some days I hate them all and every day I find something I don't like and something I love.
But Linux is my favorite OS when it comes to quickly booting up, accomplishing a particular task then shutting down quickly so you can get going and get other things done. Honestly Mac and Linux both boot fast and are ready to go in the same amount of time it takes Windows to get to the Welcome screen.
On my last computer I had a dedicated hard drive for Linux, 12 different distros. It was a project that allowed me to test drive several distros then review them for the Lockergnome Linux newsletter. I use only two for my day-to-day work, SUSE and Kubuntu (I'm a KDE fan). Over the years I've preferred PClos, Mandrake, Fedora and Xandros. I tried several times but never liked Lindows, and the BSD family is more involvement than I want in a work oriented OS.
I still haven't tried virtualization. I know it's the best solution out there, but I'm comfortable with dualbooting and with modern hard drives disk space is an affordable luxury...for a geek.
Here's something I found the other day on my web wanderings that I find quite useful as a reference tool.