I'm using
EditPlus 3, but any text editor will work. Some are made for programming and so they have highlighted syntax, auto indenting, line numbers, and so on.
Yes, Dreamweaver will work too, although you won't be able to use the design view like you can with HTML.
EDIT: Oh, and if you're planning on doing this on your home computer, you might want to take a look at
my Apache/PHP/MySQL/PHPMyAdmin tutorial. If you want to use PHP scripts on your home computer, you'll need to have a webserver (Apache) and PHP installed and configured, and then you'll need the MySQL server if you want the database functionality, and of course PHPMyAdmin to manage MySQL.