Grab a copy of Mozilla and the LiveHTTPHeaders extension. Watch to see what the server you access announces itself as. Sites that use Windows will most likely display a header that looks like:
Of course, there are many people who believe that Windows must be the best thing out there, otherwise why else would so many people use it? So they go, and they get a Windows box, and for speed they create CGI scripts based in C. I am waiting patiently for the day one of these servers gets hosed, it gets national publicity, and I get to point and laugh.
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