Currently I'm using Homesite on Win2K professional. I've used Notepad, VI, UltraEdit, TextPad, and Dreamweaver in the past. I have to say that TextPad is a sentimental favorite, but I had to give it up for something more robust.
Homesite's extended search and replace is great in v5.0 (not so reliable in previous versions). The syntax highlighting is good, but it's a shame you can't define custom templates/rules.
I'll have to check out some of the freeware editors mentioned here, like ConTEXT, PHPEdit, and SourceEdit. PHPEd sounds more and more attractive in spite of the price tag. I'm surprised not to see a single endorsement of Zend Studio though. Maybe I won't have to spend time checking it out yet...