Okay, I have some data. This is a sample from just under 200k machines, that reported back in a 2.5 month period ending in september. The software installed with one of the devices reports back data including OS. I removed the specific amounts/percents from each and combined them at the bottom. Realize this data is biased towards people who use some type of internet connection.

7 OS versions are detected:
4.10.1998 Win 98 Gold
4.10.2222 Win 98 Second Edition
4.90.3000 Windows Me
5.0.2195 Windows 2000
5.1.2600 XP Pro
5.1.2600+(Home)+ XP Home
5.2.3790 2003 Server

% 9x Platform 17.47%
% NT platform 82.53%

I have to say more 9x based than I expected.