Windows server 2008 is actually really really fast
You're right, I keep telling every body what's been written in my textbook, that Windows is proven to outperform everyone else in terms of throughput and response time in interactive systems.
For one, Windows implements some microkernel designs (ideal for webservers) whereas Linux is strictly monolithic (nicknamed "the Big Mess"). And, everything gets done faster with Windows than with Linux. In terms of open-source software, Linux isn't that great either, it's just much over-hyped. Solaris has also been proven to outperform Linux in terms of speed as well, and is actually POSIX-compliant - making it a UNIX system. Hell, even Windows comes closer than Linux to being a UNIX system using Interix. And, Open Solaris is open source and free so you can use it on your cheap web server without having to spend a dime!
I myself, use Linux for programming and to get away from Windows because much of the free opensource software out there doesn't run on Solaris. And, rather than scratching my head to figure out how to get it to work on Solaris (also a common problem on Linux) I just stick with a system which already works. It's not that I hate Linux or think it's a terrible system, it's just that it's over-hyped (much like those mac computers). Like, the mass populace are going to immediately cling to something, never willing to explore anything else, while all the Linux-fanatics spout their propaganda, preventing any up and coming mind which is willing to explore other options, from ever exploring anything else.