Notepad++ is a free source code editor which supports several programming languages running under the MS Windows environment.

Here are the features of Notepad++ :

Syntax Highlighting and Syntax Folding
WYSIWYG
User Defined Syntax Highlighting
Auto-completion
Multi-Document
Multi-View
Regular Expression Search/Replace supported
Full Drag ‘N' Drop supported
Dynamic position of Views
File Status Auto-detection
Zoom in and zoom out
Multi-Language environment supported
Bookmark
Brace and Indent guideline Highlighting
Macro recording and playback

http://notepad-plus.sourceforge.net/uk/site.htm