PHP Chatroom Tutorial Problems

I have been trying to follow this tutorial: http://www.kirupa.com/developer/flash8/php5sockets_flash8_6.htm

But when I run the BAT file, I get this error:

Fatal Error: Call to undefined function socket_create in C:\Chat\socketTut.php on line 45.

I have no idea where to go from here. I’ve trawled through some google results on it and haven’t got any definite solutions. I’ve tried using various versions of PHP with no luck. Can anyone tell me what I have to do to get this to work?