Notepad++ is a decent editor, without a doubt - but when it comes to functionality, usability, and (especially) the ability to use it as *the* editor within most any IDE or other development environment - Vim/gVim (vi too while I'm at it) is still a major slugger and a great alternative to the plethora of Windows editors out there. Given, there is a slight learning curve (*cough*), but the raw efficiency and time-saving once you become a little familiar with it is outstanding.
I am by no means attempting to hijack this thread, and apologize if it seams that way... But I most certainly do think, especially within the hack/mod community, more options and alternatives to increase productivity should be a welcome addition!