Go to www.php.net and download the latest version of PHP. You should download the windows binaries.
Unzip the file to a directory. For example c:\php
Then, open IIS console window and folow these steps: 1st In Default Web Server hit the right button and in the menu choose New -> Web Server 2nd Open the properties window of the default web server 3rd Go to Home Directory tab and hit configure 4th seek for .ida and .idq and remove them (just for security avoiding attacks from code red) 5th Hit Add 6th Executable c:\php\sapi\php4isapi.dll (or where you have the php4sapi.dll) and extension is .php 7th Go to Documents tab and add index.php, select it and hit Move Up as many times as needed until it's in the first place (now index.php is the default file to look up) 8th aplly and ok and your server is configured.