Although the Notepad included with Windows is fast and easy to use for viewing and editing random text files, the lack of UNIX compatibility made it useless for editing many files. I was using Wordpad in the case of UNIX file format, but that was awkward for its own reasons. So I switched to Notepad++ for all my text editing/viewing needs. It has syntax highlighting for many languages, tabs, UNIX file format support, zoom, regexp replace, and many other little features that are nice. Much nicer than Notepad AND it is open source.
There is also a similar project called Notepad2 but I have not used it as much because it doesn't seem to have as many features.