I initially tried the msi installer for PHP 5. Unfortunately, it installs only PHP under CGI, which although it has some performance and security issues, might be ok for a quick and dirty development environment.

But the installer is badly broken. You’ll get an error something like

PHP Fatal error:  require_once()[function.require]: Failed opening
required 'SAM/php_sam.php' (include_path='.;C:php5pear') in
sam_factory on line 1

After fighting this for a couple of hours, I ended up installing manually anyway. I used this procedure to get PHP 5 running under Vista:

1. Install the Apache webserver.
2. Get the current version of PHP 5 from http://www.php.net/downloads.php#v5. (It’s 5.2.3 at this time). Get both the zip file and the PECL zip file (which includes extensions).
3. Uninstall any previous installations of PHP 5 (Start > Control Panel > Programs and Features). You may have to reboot your machine.
4. Disconnect from the Internet. Turn off your firewall. Turn off your virus checker.
5. Turn off User Account Control (UAC).
6. Get an administrator prompt by going to All Programs > Accessories. Right-Click “Command Prompt” and choose “Run as Administrator”
7. Use the command prompt to manually remove directories containing previous PHP installations (like C:\Program Files\PHP…)
8. Go to the directory where you’ve downloaded the PHP5 and PECL zipfiles. Extract the PHP zipfile. Rename the extracted php directory (which has a name something like php-5.2.3-Win32) to c:\php. Extract the PECL zipfile into c:\php\ext.
9. In the command prompt, type:

   cd c:\php
   mkdir upload
   mkdir session
   copy php.ini-recommended php.ini

10. Open php.ini in Notepad:
    1. There are many variables… the following are important. Notice that starting a line with a semicolon in the ini file comments it out.

       upload_tmp_dir="C:\php\upload"
       session.save_path="C:\php\session"
       cgi.force_redirect=0
       extension_dir ="C:\php\ext"
       display_errors = Off
       log_errors = On
       error_log = "C:\php\error_log"

    2. You might want to look at upload_max_filesize. I’ve set mine to 16M. I also set post_max_size = 16M.
    3. Enable the extensions you need by deleting the semicolon at the beginning of the line. These will depend on your application… I’m going to be using MySQL (which I’ve already installed) and Moodle (which I’ll install later). My list looks like the following:

       extension=php_bz2.dll
       extension=php_curl.dll
       extension=php_dba.dll
       extension=php_dbase.dll
       ;extension=php_exif.dll
       extension=php_fdf.dll
       extension=php_gd2.dll
       extension=php_gettext.dll
       ;extension=php_gmp.dll
       ;extension=php_ifx.dll
       ;extension=php_imap.dll
       ;extension=php_interbase.dll
       extension=php_ldap.dll
       extension=php_mbstring.dll
       extension=php_mcrypt.dll
       extension=php_mhash.dll
       extension=php_mime_magic.dll
       ;extension=php_ming.dll
       ;extension=php_msql.dll
       ;extension=php_mssql.dll
       extension=php_mysql.dll
       extension=php_mysqli.dll
       ;extension=php_oci8.dll
       extension=php_openssl.dll
       ;extension=php_pdo.dll
       ;extension=php_pdo_firebird.dll
       ;extension=php_pdo_mssql.dll
       ;extension=php_pdo_mysql.dll
       ;extension=php_pdo_oci.dll
       ;extension=php_pdo_oci8.dll
       ;extension=php_pdo_odbc.dll
       ;extension=php_pdo_pgsql.dll
       ;extension=php_pdo_sqlite.dll
       ;extension=php_pgsql.dll
       ;extension=php_pspell.dll
       extension=php_shmop.dll
       ;extension=php_snmp.dll
       extension=php_soap.dll
       extension=php_sockets.dll
       ;extension=php_sqlite.dll
       ;extension=php_sybase_ct.dll
       extension=php_tidy.dll
       extension=php_xmlrpc.dll
       extension=php_xsl.dll
       extension=php_zip.dll

11. Right-Click on Start > Computer. Choose “Properties”, then “Advanced”. Click on “Environment Variables”. Click on PATH, then Edit… and add “;C:\php;c:\php\ext” (without quotes) to the end of the variable.
12. Open your Apache configuration file (All Programs > Apache HTTP Server 2.2.x > Configure Apache Server > Edit the Apache httpd.conf Configuration File). Add the following lines:

    LoadModule php5_module "C:\php\php5apache2_2.dll"
    AddType application/x-httpd-php .php
    AcceptPathInfo on
    PHPIniDir "C:\php"

    Look for the DirectoryIndex line. Add ” index.php” (no quotes) to the end of that line.

    Save the file.

13. Create a file named test.php in your Apache htdocs directory, containing this text: <?php phpinfo(); ?>
14. Reboot your machine.
15. Browse to http://localhost/test.php. You should see tabulated information about your working PHP installation.