On Windows, platform.system() (and platform.uname()
[0]) return 'Windows' or 'Microsoft Windows' depending 
on whether win32api is available or not. This is 
confusing and can lead to hard-to-find bugs where 
testing in one environment doesn't reveal a bug that 
only occurs in another environment.

I believe this hasn't been fixed in Python 2.4 yet  (only 
the XP recognition has been fixed, it is also broken in 
2.3 when win32api was available).