I use Linux Mint myself, but I've also used Slackware, Knoppix, Red Hat (before Fedora), and Yellow Dog Linux to name a few. Me and my brother once donated to the Free Software Foundation, and I donated a little to the Inkscape project once.
I used to not mind paying for Windows that much, but everything is so locked down now. You can't lend out a copy or transfer it to another computer. Also, I don't like how Microsoft basically rents its software now. Once you pay for software, it should be yours to use forever. I know that when I buy something, I don't alway get around to using it right away.