os.walk(entire filesystem)

[rbt]

More of an OS question than a Python question, but it is Python related 
so here goes:

When I do os.walk('/') on a Linux computer, the entire file system is 
walked. On windows, however, I can only walk one drive at a time (C:\, 
D:\, etc.). Is there a way to make os.walk() behave on Windows as it 
behaves on Linux? I'd like to walk the entire file system at once... not 
one drive at a time.

Thanks!