Man... This is not "ProIIS" argument", it's commun sense! I'm in charge of managing + developing for a big site, I've been put in charge and did not had the choice of server... they said "Use the Apache thing with CGI/Perl - PHP under Unix"!
I did it, developing for this thing is slow, running it is slow, we had to put a super server! We use tools and developing techniques that was cool 15 yeasrs ago! Try debugging Perl... try tracing it!!!
Now, 4 years later I finally got the ok to at least port a few apps on the IIS 6.0 server... man... the thing does rings around Apache, you can deal with cache in a way you can't even dream in Apache!
Run a site Unix/Apache/PHP, port it to IIS 6.0 in ASP.NET and see the difference!!!
My point was that I can hardly believe that 3 years ago, on netcraft, it was said that IIS had around 40% of the market, now it around 22%. I would have like to have some info on wath the ... you think of Netcraft, are they really impartial ?