Note that I primarily work in C/C++. For C/C++ code, I use Visual C++ Express Edition or Visual Studio Professional. For the little bit of Python I'm learning, I use the editor in the PythonWin IDE. (Mostly because it does a bit of code completion.) For everything else, I use GViM.
Tip:
After you install ViM on Windows, if you right-click on any file in Explorer, you see the Edit with Vim option in the right-click menu. This is very useful for peeking into and editing every kind of text file without having to bother about specific editors. GViM can understand most formats and thus displays them with syntax coloring. Get used to doing this and soon GViM becomes your defacto generic text editor on Windows. (Even replacing Notepad.)
