PHP 4 or 5 is good?

PHP4? huh? – you still thinking about this? – dont do that!

Support for PHP4 has been discontinued since 31 December 2007. There will be no further development for this version. So it is highly recommended that you should code new websites and programs in PHP 5.x only. Also, if possible try to upgrade your existing applications also to PHP 5.x.

PHP 5.2.5 is the latest stable version at present (as on 03 Mar 2008). You can find some of the new features at http://devzone.zend.com/node/view/id/1714

You can download the PHP Source code and binaries from here.