The Windows version of PHP now exposes a set of constants prefixed PHP_WINDOWS_* . A list of these constants and their usage can be found at http://docs.php.net/manual/en/info.constants.php
Warning Support for the ISAPI module has been dropped. Use the improved FastCGI SAPI module instead.
Note: A new dedicated site for PHP on Windows is now available, including downloads, release candidates, and snapshots in various flavors (thread-safe/not-thread-safe, VC6/VC9, x86/x64). http://windows.php.net/ .
User Contributed Notes
“ Well worth the effort to set up fast cgi on windows. No more lockups with php or 40 procs running...and 1 killing IIS. Some PHP INI vars can't be overriden in your php files, so read up (like timeout). 8 months and no more locked up iis.“
“ Fast CGI is available for IIS6. Reading the IIS website (which is more appropriate since it is server specific) yields plenty of results regarding PHP setup under the fastCGI module. They even have an entire domain associated with PHP.”