Originally Posted by Elfwreck
...If you can live without WYSIWYG, PortableApps.com has Notepad++
... you can get a semi-WYSIWYG enviornment (read: quick preview) by opening the HTML file in both Notepad++ and a browser. You then make some edits, save, and click the refersh button in the browser to view the changes.
I also find the WebEdit plugin for Notepad++ a very handy addtions. I've customized mine with a number of tags that I commonly use in eBook HTML.