There are a bunch of PHP IDEs that are much better than Dreamweaver. Many are free as well.
The IDE I use is PHPEdit, available from www.waterproof.fr. It is a good editor, although the code completion only has an insert mode and not an overwrite mode and its "quick mark" feature is a little annoying. You can get the trial version, buy the professional version, or you can get a personal liscense if you tell them that you won't use it for commercial purposes (and if you do happen to use it for commercial purposes, well, I won't tell).
There are many more. For a good selection, check out www.php-editors.com.