I think it’s important to understand how your applications work without the aid of an IDE.  But man, oh man.  It sure is nice to have a good IDE while you are trying to be productive in a language.  I installed PyDev today now that I feel very comfortable with how python applications are built and run.  It is so nice to explore what’s available by just typing code.  In my IDE, I can just type “platform.” wait a sec and see all my available options.  I’ve been using TextMate for the better part of two years now.  It’s a great text editor, but it sure is nice to have a full featured IDE to not only write the code, but see warnings and errors very quickly.  It’s nice to see the structure of my code in the outline view.  By far, my favorite feature is the integrated debugging.  Setting breakpoints, stepping through code, and inspecting variables is a beautiful thing.