Zend Studio

ZEND STUDIO integrated development environment (IDE) for PHP developed by Zend Technologies, based on the PHP Development Tools.
This Zend studio is not an open source it comes with an commecial license which u need to buy.But this zend studio provides the best IDE for working in linux environment.

This will be the best substitute for ADOBE DREAMWEAVER in windows.Zend Studio is tightly integrated with Zend Server, Zend's pre-integrated, tested PHP application stack. The integration enables developers to quickly set up a complete PHP environment and speed up root cause analysis of problems detected in testing or in the production environment.

Zend Studio is also integrated with Zend Framework. For example, it provides an MVC view for easy code navigation and integration with Zend_Tool for automated code generation
There are also other IDE which provides very good environment for developing PHP based projects.

ZEND EDITOR

Step 1:
Download the trial version of the Zend Editor from
http://www.zend.com/products/studio/

Step 2:
Extract and install the bin file.After extracting it.

Step 3:
Type in any user name and try the following keys in the Zend studio

3A1A13A4C070DA103A4C070D
329294E5B730B2974E5B730B
3ACACC8F052A8ACFC8F052A8
3A5A533A7A777A5033A7A777
325255467938525654679385
31717C97025B917FC97025B9
32E2EA22E161D2E9A22E161D
32727509243B8276509243B8
3AFAF2ED999ECAF12ED999EC

STEP 4:
Thus u installed Zend Studio

Other PHP IDE are

KOMODO EDIT

Komodo Edit is a free text editor for dynamic programming languages introduced in January 2007. With the release of version 4.3, Komodo Edit is built on top of the Open Komodo project.

Komodo Edit inherits many features of Komodo IDE, like the full range of supported languages (Perl, PHP, Python, Ruby, Tcl) and platforms (Linux, Mac OS X, and Windows ). And like Komodo IDE, Komodo Edit also supports browser-side languages like JavaScript, CSS, HTML, and XML.

It was developed for programmers who need a multi-language editor with broad functionality, but not the features of an IDE, like debugging, DOM viewer, interactive shells, and source code control integration.

Aptana Studio
Aptana Studio is an open source integrated development environment (IDE) for building Ajax web applications. It includes support for JavaScript, HTML, DOM, and CSS with code-completion, outlining, JavaScript debugging, error and warning notification and integrated documentation. Additional plugins allow Aptana Studio to be extended to support Ruby on Rails, PHP, Python, Perl, Adobe AIR, Apple iPhone and Nokia WRT (Web Runtime).