TeXnicCenter

From ToolsCenter.org:

IDE means the integration of all the tools needed to develop documents with LaTeX into just one application. You have the editor to write your LaTeX files with, you can start the building process just by choosing a menu item and the output of the LaTeX compiler is written to a window of TeXnicCenter and analyzed, so that you can simply jump from one error, warning or bad box to another one.

Also viewing the generated output is easy with TeXnicCenter. Just choose a menu item and the correct viewer application will be started and if supported by the viewer, the output will be displayed at the position belonging to the current source position in TeXnicCenter.

And the best: TeXnicCenter is distributed as open source under the terms of the GNU General Public License (GPL) and is consequently available for free.

TeXnicCenter's aim is to support the LaTeX-newbie by providing him the most important LaTeX constructs via menu and by abstracting the use of the LaTeX compiler and other tools like MakeIndex and BibTeX and even support the LaTeX-pro by providing a powerful, fully customizable integrated environment.

To avoid misunderstandings: TeXnicCenter is not a WYSIWYG (what you see is what you get) interface for LaTeX and will never be, because we think that providing such an interface for LaTeX can not benefit from the advantages of LaTeX.