J. Christopher over att Monday By Noon has written an article about Linux and Web Development, a quite nice intro for people being afraid of switching environment.

However, although Linux supposedly should be free and open source I would like to mention the one tool I cannot live without, Zend IDE which is first and foremost an IDE (integrated development environment) for PHP but has alot of features for plain HTML programming as well.
Auto-completion, code templates, debugger (both local and remote) and MySQL support is just some of the features.

If you are serious about web development in Linux and don´t want to learn a zillion keyboard shortcuts in Emacs, Zend IDE is a great tool.