I have recently started to use Notepad++ more and more for my code editing (both C source code and scripts). Notepad++ is a free (as in “free speech” and also as in “free beer”) source code editor and Notepad replacement that supports several languages.
The editor is a multi-Language environment that has syntax highlighting and syntax folding (ready made for many languages and can be user defined if needed). It has also PCRE (Perl Compatible Regular Expression) search/replace, multi-document tab interface, bookmarks, auto-completion, WYSIWYG (Printing) and macros (recording and playback). If you need a good free all-around code editor that runs on Windows, check out Notepad++.