I use Gentoo Linux, Mozilla Firefox, a lot of little UI tweaks to get things just right, and no more closed-source software than I can count on one hand (video drivers and the copy of Opera for testing my creations included). (Games are exempt since I have yet to see proof that the open source development model will work for "throwaway software")

I also default to ACCEPT_LICENSE="-* @FREE freedist nosell" for my Portage 2.2 settings, which basically means I'm approaching Stallman-level "free software and nothing else" behaviour.

On the other hand, I write programs for fun and I'm quite comfortable spending a fair bit of time in a slide-down terminal like Yakuake, so it's something that works for me.