• PSPad

From author's site:

PSPad is a freeware programmer's editor for Microsoft Windows operating systems, useful for people who:

* work with various programming environments
* like highlighted syntax in their source code
* need a small tool with simple controls and the capabilities of a mighty code editor
* are looking for a tool that handles plain text
* want to save time - PSPad offers rich text formating functions
* need tool what offer user extension capabilities
* want to save money and still have the functionality of professional products because PSPad is free for commercial and government purposes too