There's no such thing as PHP hardware, so I assume you mean software. Since PHP is mostly useless without a Web server, you need to check for that first. Try typing 'localhost' into the location bar of your browser. If you see 'Page Not Found', you need to install a Web server (probably Apache). If you see an actual page, then you already have a Web server.
Next step would be to find out where the Web root folder is on your computer, add a simple PHP script, and then try to view it in your browser. If that works, you have PHP installed already. If not, then you don't.
You'll probably need more assistance with this, but I'd recommend heading over to the installation forum for that once you know where you are in the process. Have fun...