Linux vs Windows 7 Web server performance differences

I've tried recently to run some benchmarks and I wanted to check something on Windows and I had discovered huge performance differences between basic HTTP web servers on same machine with Linux and Windows.

I've tested several web servers IIS, Apache2, Lighttpd with different clients Apache's ab and my own client and the result was the same (requests per second) id displaying a
simple HTML web page (default web server page) of a several hundred bytes size:

           IIS 7.5   Apache 2.2  Lighttpd
Windows    750         800        -
Linux      -         9,300        22,000

I've tried to disable Anti-Virus on Windows but the result hadn't changed.

I don't understand one thing, how on same hardware (i5 2.4GHz 4G)
a web server in the most trivial task can't handle same loads.

Even thou I'm "pro-Linux" I still can't get how can it be so different, Both
64 bit latest operating systems (Linux 2.6.35 and Windows 7) but
yet the difference of an order of magnitude.

Environment:

• OS Windows 7 64 bit pro. Linux Ubuntu 2.6.35
• HW i5 2.4 GHz, 4GB memory
• IIS 7.5, Apache 2.2
• Client ab:
• Called as ab -c 5 -n 10000 http://127.0.0.1/

Question:

• What can I miss so I get to huge differences?

Before You Vote To Close:

Note it is a real question as I'm looking for possible factors that can affect
such huge (order of magnitude) performance differences as I can't believe that
Windows can behave so badly.

Anybody?