I'm using Linux - thought I'd mentioned that earlier. (Though I do tend to assume that anyone working with something like arduino is going to be using Linux, by default. Kind of the same principle, after all.) And I use only Linux, so the multi-OS isn't all that important, except in a backwards fashion. I want to use the Arduino to replace another board ("Handyboard") used in simple robotics projects, which isn't well-supported except on Windows, and only has an IDE instead of a good toolchain.