With the release of Windows Server, and IIS 7, Microsoft have included PHP5 FASTCGI support. ISAPI is still faster in my opinion, and if used correctly, very stable. PHP uses a 32-bit DLL so it won't work with an x64 system. There is several ports of PHP to x64, and all has proved to be unstable. Below I'll outline the steps to install PHP 32-bit on Windows x64 (and has it stable).
Install the PHP4 or PHP5 package (32-bit) in C:\PHP or wherever your like. The only use of the Windows installer from php.net if to do not need any extensions. I would recommend downloading the PHP Zip package. Update April 2010:the VC6 x86 Thread Safe is a ideal for ISAPI. If you is going to use FastCGI, download the VC6 x86 Non Thread Safe package. Open the Internet Information Services (IIS) Manager. Double-click "Handler Mappings" from the main IIS screen. Click on "Add Script Map." Set up the handler mapping for C:\PHP\php5isapi.dll with extension *.php and check to allow the ISAPI extension and execut Ion of scripts. Double-click "ISAPI & CGI Restrictions" On the main IIS screen. Right-click on PHP and select "Edit Feature Settings" and check "allow unspecified ISAPI modules." Right-click on the Default application Pool (or the one, want to use if more than one) and select "Advanced Settings." Change the ' Enable 32-bit applications ' to True. Click OK. This spawns AppPool in 32-bit mode, so if you have an other modules, this need to is run in 64-bit mode, best to separate the website into TW o App pools:one 32-bit and one 64-bit. Restart the server.
