I like to use NuSphere PhpEd because I write a lot of php code and it has code completion for CSS. The code completion it's not that great for begginers but if you have to write fast code the completion helps a lot. And the editor is much faster that the other ide's like zend or komodo or let's say dreamweaver.
IMO it's great. I've been using it for so long I've become very comfortable. Love the CSS editing functionality. It's not the end-all be-all though... I think it's extremely important to learn to hand code too.
I sue PSPad. I really like being able to pull up CSS/HTML/PHP documents from my webserver and modify them directly. Works out great when I am doing a WordPress theme.