These are the steps for manual installation of PHP version 5.2.6 with Apache HTTP server version 2.2.9 on windows Vista.
Download Apache HTTP Server from the following link.http://httpd.apache.org/
Download the latest zip package of Windows Binaries from the following link.http://www.php.net/downloads.php
Extract the zip binary package into C:\php folder.
Add the PHP directory to the PATH as follows.
click start -> settings -> control panel -> System.
click on Advanced system settings (appears on left side of the window)
click on the 'Environment Variables' button
scroll down to find 'Path' in the System variables pane.
Double click on the 'Path' and add ;C:\php at the end and click on the ok button.
Restart the system.
In the php folder look for the file 'php.ini-recommended' and rename the file as 'php.ini'.
Copy the 'php.ini' file into 'C:\windows' folder.
Rename the 'php.ini' file in 'C:\php' folder to 'php-activescript.ini'.
Download 'php5activescript.dll' from the following link.http://pecl4win.php.net/list.php
place the DLL in 'C:\php' folder.
Register the DLL as follows.
Click on the Start -> Programs -> Accessories -> Command Prompt.
In the Command Prompt window go to 'C:\php' and type regsvr32 php5activescript.dll
Changes to be made to httpd.conf file of Apache:
Look for 'httpd.conf' file in the folder chosen for installation of Apache software.
(By default the file may be located in C:\program Files folder.)
Add the following line in the LoadModule segment of the conf file.
LoadModule php5_module c:\php\php5apache2_2.dll
Add the following line in the segment of the conf file
AddType application/x-httpd-php .php
save the changes and close the conf file.
Restart the Apache server.
Reference : PHP Installation Guide.
PhP | Windows | Vista