This article is old. Be careful! It might contain outdated information.
Here's an alternate resource that I am recommending for this topic.
This article is meant as a heads up for all those who are running PHP on Windows XP or Windows Server 2003.
As of PHP 5.5 The PHP Group has dropped support for the above mentioned operating systems. Although I don't see why anyone would run PHP on a Windows machine, I know that there are a lot of servers out there that function with these technologies.
Although this announcement, following the release of PHP 5.5 back in 2013 hasn't received as much press as deserved, I thought that coming back to it and pointing out that future "bug fixes" and "security updates" in PHP will not target Windows XP and Windows Server 2003 which is the main reason you should consider changing server configuration as soon as possible.
Further details are available on the PHP website along other important backward incompatible changes added in PHP 5.5.
PHP 5.6 stable is coming fast. It is now at Release Candidate 3 and most likely will soon be available for production environments.
Before you get all excited about the news and decide you want to upgrade your PHP version, you should know that two important functions have suffered important changes that might break your code.
The json_decode() function will now reject non-lowercase variants of JSON literals true, false and null. Also, all mcrypt_*() functions will fail if called with wrong key sizes or initialization vectors. Previously, calling mcrypt_encrypt() without an initialization vector used to only throw a warning so be careful and revise your code before upgrading.
More changes are available on the PHP website along other important backward incompatible changes added in PHP 5.6.