Elizabeth Smith wrote up a great explanation of FastCGI and the reasons it makes Windows a better host for PHP applications. In the opening, she writes:
Today at TechEd IT Forum in Barcelona, Bob Kelly announced the official release of the FastCGI Extension for IIS 6.0. This means customers now have reliable, high-performance hosting for PHP and other CGI-based applications on production Windows servers with full support from Microsoft.
You may have heard about the new interoperability improvements for PHP and Microsoft technologies that Bill Staples blogged about. A few weeks ago, I spoke at PHP|Works in Atlanta and showed off a project I've been working on to demonstrate how PHP applications can take advantage of the new features of Internet Information Services 7.0 (IIS7).