www.phpfreaks.com
www.zend.com
www.php.net
those are the only links you really should need, they give lots of great info and in the case of php.net its some of the best documentation out there!
Oh, and if you need a nice all-in-one and easy to setup testing platform (for windows) check out phpdev, it
installs apache, php, mysql, phpmyadmin, and a simple ftp server so you can have a nifty testing environment with minimal hassle.

