"... On a Windows platform, there is competition from ASP and Cold Fusion. Here the choice can be as much political as technical, and ASP with IIS is probably a safer bet than PHP with IIS. But on a purely technical basis, PHP is as stable on WindowsNT as either of the other two, at least as fast and less resource intensive. However, ASP offers far better integration into the underlying operating system and databases, especially if you want to make use of COM."
According to NetCraft surveys, PHP is now the most popular module for the Apache server and in total running on something like two million Web sites. Here are some of the reasons why PHP is such a popular server side scripting language.