Try PHP Designer 2007 Personal (Freeware) Edition at http://www.mpsoftware.dk/downloads_achieve.php. The version is no longer maintained, but it may work for you. I tried PHP Designer and really like it, but settled on PhpED. Good luck.
I'm using programmers notepad, or sometimes eclipse, but the last one is using to much memory (but its full of features and you can use it with frameworks too)
Hapedit also good (neat and simple) and there are plenty of free editors there.. Have a look this site: http://free-php-editor.com
If you like to use commercial software, then purchase for Dreamweaver (adobe dw cs4?) If you like to use free software, use Notepad++ (Npp)
I'm a big fan of the PHP Designer 2008 software... it may lack the WYSIWIG of dreamweaver, but it's a powerfull PHP editor ^^
I use Linux, so I've tried out a lot of the options for Linux. I've pretty much settled on using OpenKomodo. There is a full commercial version called Komodo IDE, but I've found the open source version suits my needs perfectly. One nice thing about it is there are Linux and Windows versions, so I can use the same software on Windows at work.
Zend Studio for Eclipse. Worth every penny, if you don't want do buy it then you can get hold of Zend PDT for free, which is almost as good, its just lacking in some features.
I used dreamveawer but it don't provide preview of webpages with php content, so I got to this setup now which works quite good for me XAMPP-Php & Mysql on my Pc which enables me to run PHP pages on FF and I use notepad so its no waiting for pages to load and I can check my code in FF instantly.
That's not entirely true. Dreamweaver comes with the feature of Live Data Here's where you find it You will need to set up the testing server locally first in your manage sites section however