I have tried many IDEs like NetBeans but most of them require to setup a project and do settings and blah blah blah. I need a simple editor like a Notepad++ with following features. 1. CSS editing 2. Function completion with its discription and arguments. 3. Syntax checking as one types.
I'm personally a big fan of Zend Studio. However, if you're looking for a 'lite' IDE, it's probably not the best option. It works at its best with quite a bit of memory and can really lag your computer while it's running if this isn't the case. Nevertheless, it's still one of the best one's I've used, doesn't require any 'setup' (only declaring which PHP version you use, so it can syntax check). The newer versions might require you to create a project, though I didn't play with it that long. 5.0 (the version I use) doesn't.