It sounds like you're bordering on a full-scale IDE (time to buy more memory).
As I understand it, Zend's IDE is the favorite of PHP developers (well, now it's been integrated into Eclipse, and some don't like it as much anymore), much like IDEA is wildly praised by Java coders. However, those both cost money.
I do very little PHP coding, but just use Eclipse for the contextual popups it provides. It may have refactoring and all that, but I don't remember. Either way, Eclipse is pretty popular for its language support.
I use NetBeans for Java and C, which is quite the heavy IDE (like Eclipse), but it's the best free Java IDE available (it's now funded by Sun), and is close to being able to compete with Eclipse for language support.
I've probably not been too helpful for a light source editor. Notepad++ is the only thing I know of for windows, and for that sort of stuff, I usually use gedit/vim on linux (both have bare-bones syntax highlighting for virtually any language).