I've been using RapidPHP 2007, along with notepad2, An MS notepad clone with syntax highlighting. Although it doesn't allow multiple instances. I found it on sourceforge years ago. Its very similar to notepad++.

Typicaly... i do all my web coding, php, html, css, and js in RapidPHP. Small, minor edits i'll do in notepad2.
I havent tried any other IDE's though.

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