Here are some great links to check on:

PHP.Net

PHP/FI 2.0 Source and related files

php-4.0.6.tar.gz

PHP 4.0.6 - gz format Complete Source Code package [3,083Kb] - 23 June 2001

php-4.0.5.tar.gz

PHP 4.0.5 - gz format Complete Source Code package [2,621Kb]

php-4.0.5-Win32.zip

PHP 4.0.5 - zip format Complete Source Code package [4,590Kb]

php-4.0.4pl1.tar.gz

PHP 4.0.4 - gz format Complete Source Code package [2,382Kb]

php-4.0.4pl1-Win32.zip

PHP 4.0.4 - zip format Complete Source Code package [3,737Kb]

php-3.0.18.tar.gz

PHP 3.0.1 - gz format Complete Source Code package [2,167Kb]

php-3.0.17-win32.zip

PHP 3.0.1 - zip format Complete Source Code package [1,852Kb]

time_jpeg.zip

Time & Date script by loading a JPEG and writing on it. Example.