What operating system does it run on?
theWord has been developed for the Windows operating system and is compatible with Windows 98 upwards (including Windows XP, Vista, and 7).
Some of the unicode features are not available in older Win9x systems. There is special support for localized Win9x systems though (e.g. Arabic Windows 98 will properly display contextual shaped Arabic text). In Windows 2K upwards, there is full support for all languages.
(From TheWord.net website: http://www.theword.net/index.php?faqanswer.56&l=english)
Having said that, let me quickly add, using WINE (Windows emulation software) for both the MAC and Linux, you can easily run the program on both of these platforms. I have had many, many communications with people daily using theWord on both of these platforms.
In the video below (from Doug Hamp), skip to minute 13 to see discussion of this.
This following link is from codeweavers, and I have a little more confidence in it.