win2k and lower are absolutely useless out of the box, and to expand on their functionality is to increase their footprint significantly. Im inclined to say the same about XP, although MAYBE you could get on the internet out of the box with included drivers? Vista is a stop gap between XP and windows 7 and isn't worth regarding in this argument (which I was under the impression was about which OS runs best on low resource platforms), and im not sure Windows 7 is either. I do see some netbooks coming with windows 7 starter/home/basic or whatever the **** it's called, not sure how well they run though, and the name implies that there is something lacking from those and the "better" win7 versions.
Bottom line, there really is no Windows release that can beat linux in a small footprint race, Windows is simply not modular enough to do it. Case in point, can I run windows sans GUI?
(and before you say that would be useless, let me state for the record that I have a fully functional system that runs a large % of console based apps, most of which are better than their windows counterparts)
I like linux, other people can like what they want.
I would rather run windows for certain windows-only software than say, use wine.