Scribus is an open-source Desktop Publishing program, capable of doing brochures, newsletters, magazines, newspapers, and things like that.
This program has been available for other operating systems but only recently released for Windows.
Although it is not quite as powerful as Quark XPress or Adobe InDesign, those programs cost hundreds of dollars, where as this is free. It is a bit more difficult to pick up than those other programs, unfortunately, and can be particularly difficult if you aren't familiar with desktop publishing programs, but it is very powerful and very capable.
Scribus runs on Windows, Linux, and Mac OSX.