Writing long code in Notepad is a nightmare. If you aren’t already cultishly attached to a text editor and are looking for a nice Notepad replacement, be sure to check out Notepad++. I’ve been using this for coding for quite a while and I really like it. Languages supported are C, C++, Java, C#, XML, HTML, PHP, Javascript, RC file, makefile, nfo, doxygen, ini file, batch file, ASP, VB/VBS, SQL, Objective-C, CSS, Pascal, Perl, Python, Lua, Unix Shell Script, Fortran, NSIS and Flash action script.
Download.com describes Notepad++’s main features:
Notepad++ main features are: Syntax Highlighting and Syntax Folding, User Language Define System, Regular Expression Search, WYSIWYG (If you have a color printer, print your source code in color), Unicode support, Full drag-and-drop supported, Brace and Indent guideline Highlighting, 2 edits and synchronized view of the same document, User Language Define System.
There are also line numbers (of course) and loads of other features! I’ve recommended this to a few of my friends and they’ve loved it too.
Screenshot:

Click here to download Notepad++.