Zend IDE. Although I've some pretty close runners up, unfortunately I don't recall their names.

To the guys still using notepad... is there a reason you're not using an IDE? In case you don't know, your missing out on loadsa nifty little features, such as code completion, syntax highlighting, debugging tools, profilers, etc. :)

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Any fool can write code that a computer can understand. Good programmers write code that humans can understand.