Phil Oye

X vs. XP compares the usability between the two big operating systems and it is relatively even handed about it, even including a page about bias.

What I like about the site is that it goes feature by feature, from high level to the nitty-gritty. For example, pages about login, web serving, screen capture, dialogs, drag and drop, etc.

The methodology for determining an overall winner is highly questionable, but what are you going to do? It still comes up with the right answer.