Here's the minimum that you'll need to get the most from this book:
A development workstation, running either Windows or Linux with a basic text editor or development environment of your choice, and a Web browser to try the examples.
A development server running PHP, which needs to be configured roughly in line with the setup detailed in Appendix D.
A network connection between the two.
Ideally, you should try to secure the following:
An Internet connection there are lots of URLs scattered throughout this book, and you'll need an Internet connection to go see them.
Lots of free time!