EditPlus2 FTW. I've heard good things about Notepad2 also.
Currently I use Dreamweaver as it hints (I've still not got past spelling colour with a 'u'). It's not exactly WYSIWYG but close enough. I usually just preview in multiple browsers.
IMO, SciTE is fantastic for pretty much all text-based editing. I agree with cthu1hu; EditPlus is worth looking at. It has a browser built in, which is good. What is not so good is it uses the IE renderer!
I've never been a big fan of WYSIWYG editors - I like to know I did it aaall myself! ;)
In my opinion I say Dreamweaver is a WYSIWYG because you have the design view and the code view. While you type the code you see the results instantly.
This is not the same as in Editplus and and Notepead ++
I sadly use Dreamweaver and Microsoft Expression Web. :O I am not talented with web development yet so I need something that is super easy and straight forward.