There are good TeX-writing environments and editors for most operating systems; some are described below, but this is only a personal selection:
TeXtelmExtel (systems/msdos/emtex-contrib/TeXtelmExtel) is a Shell for emTeX or WTeX and related tools under Windows. It includes a simple multiple-document editor, a built-in spelling checker, automatic OEM/ANSI character conversion, user-definable point-and-click Templates, support for the forward and inverse search mechanism of DVI driver for Windows and for automatic font generation. Besides the predefined tools, up to 10 user-defined tools can be set up.
On a PC with large enough memory, a version of GNU emacs, that will run under Windows, is available; thus you can also use AUCTeX under Windows.
Y&Y's commercial (and high-quality) Windows previewer, dviwindo, can be used as a good TeX shell, calling programs such as TeX, drivers, and editors (Y&Y supply the public domain PE, and recommend the commercial Epsilon) from customisable menus (see commercial vendors for details of Y&Y).
Scientific Word is a WYSIWYG editing program, strong on maths, which uses LaTeX for output (see vendors for contact address).
There is another set of shell programs to help you manipulate BibTeX databases.