It's primarily created for Windows XP; it could run under Windows 2000 or Linux's VMWare or Wine. LaTeX is a higher layer of the program; there is some XML running inside. You may control the program much like other WYSIWYG editors but the subtle combination of the physical and logical formattings allows you many new things - such as changing the layout of your document by a single click. All features of TeX are available together with spellcheck and other things.
Some of you should check this program. You may download it after you register at the MicroIMP forums. Micropress Incorporated has done a lot of work to make TeX visual - e.g. VTeX - and you may look at their website, too. Even if you don't speak Czech, you may find this article useful because of the screenshots.