I'm running Ubuntu on an ancient G3 Mac. I'm really pleased with it. I've been trying to find a distro of linux that I really like since back in the Slackware 1 days. I think Ubuntu is it!

On the GTD side, I've been using Jpilot and am happy with it for most things. Syncs nicely with my Palm and even lets me use pedit's p32 database. I've been trying Emacs modes and have tried Planner, Org and Howm. Spent the weekend playing around with Planner, but it just doesn't seem like a good fit. Org is nice and I like all the export options. Having a lot of options on the menu makes it easier for new users to learn. What I'm most interested in is Howm and I think I'm moving back to it. I even posted some screenshots here:
I like the way that you don't have to do anything to make the linking happen. And I especially like being able to just dump stuff into a file and have it find it for you. I've been looking for a good way to search for stuff and this seems pretty straight forward. I just wish there was better documentation as there seem to be a lot of features that I just don't understand :)