I think the author of the book really really really regrets mentioning that website, as it has been down for quite some time, and lots of people have commented on it.
The best, and official place for PHP is at
http://www.php.net where you can download the most recent version, 4.3.2
I haven't read the book so I can't be sure you don't get all the stuff you need mentioned in the book, but most people can apparently live without it as the site is down ;)
Cheers,
Imar