I'm using only linux right now, where everything down to the source code is tweakable. Now, I'm sure that OSX isn't open source, but is it less restrictive than Windows as far as customizing? (Just an example: background processes. Windows makes sure that they're all interconnected, so killing one will usually crash the machine, whereas in linux you can select processes independently). I'm just trying to learn a little more about these systems, as they sound like they would be a great alternative for my father (and maybe I won't have to reinstall his printer every 4 days ).