If you're building a small, simple website Notepad is fine. Otherwise it's absurd. I use Photoshop to design my layouts and slice them, Dreamweaver to edit the sliced layout's html, and a free program called Notepad++ for coding the PHP by hand. If you're only using HTML/CSS for your site, don't waste your time with Notepad. Dreamweaver is 1000 times faster if you know how to use it right.
Dreamweaver is a killer for designing sliced templates, can notepad do that? Can notepad pick a certain selection of a psd template and code it? Of course not, all you notepad users should just grow up.