Sometimes you'll have a need to install PHP on Windows to run a CMS or framework that requires it.
This guide applies to Windows 7 and Windows Server 2008 R2. Vista and Server 2008 should work, but you'll have to install IIS 7 Administration Pack to get FastCGI support in IIS.
In this case, I've used this guide as a base to get SilverStripe working on Windows, but the idea can be used for other applications like Drupal, and Wordpress.
I've also written an expanded guide on the SilverStripe documentation site if you're looking for more information.
Finishing up in PHP Manager
php_sqlsrv.dll (if you need SQL Server support in PHP)
date.timezone = "Pacific/Auckland" (or whatever your timezone is from this list of support timezones in PHP.
post_max_size = 64M
memory_limit = 256M
upload_max_filesize = 64M
Restart IIS so all configuration takes effect.
Now you should have PHP up and running on Windows, and have a clean way of managing the configuration from IIS Manager, thanks to the very useful PHP Manager for IIS extension.