Everybody has their pet gripes about one or the other, but I'm curious if there is any actual science showing that "The Windows Way" or "The Mac Way" is significantly better for some task.

Just to be extra clear: I do not want to know what you think is better, or even what great designers think is better: I want links to and summaries of peer-reviewed scientific literature. I will also accept studies concluding "approach X is better than approach Y," where it is clear that Mac does X and Windows does Y, even if the study does not specifically mention either. Bonus points for studies that throw in Gnome, KDE, or other lesser-known (but real!) graphical user environments.