Notepad/Wordpad combo all the way. That is what I learned PHP & HTML on... and now I also use Dreamweaver, although I know it has it's faults- I still love it like a dysfunctional child.
I think that learning with notepad/wordpad is the best way to go... it's like eating saltines for a year, and then suddenly someone puts a big bowl of chocolate pudding in front of you. Yeah, it's not perfect and it will probably make you sick, but WOW you are SO impressed with how much better it is than what you had.
I still code PHP in notepad/wordpad but I'm considering taking the plunge and getting that chocolate pudding as it were.
Some good PHP Editor ideas on here.. thanks!
-Elizabeth