If I have to use something like Notepad, I will use Notepad++, it is created for coders and designers, I like it very much. If you can afford Dreamweaver, buy it. It is a really good, easy to use program. It works not only with PHP and HTML/CSS but also JavaScript, XML.
I use DW CS3, one year ago I used DW 8 but I switched to CS3 because DW 8 had some bugs what were fixed in the last version.