I have used both MS Word and Microsoft Publisher to do this. Here is the difference.
With Word, all of the content must "flow". If you insert something preceding something else, all of the text, graphics, etc that follow the element that you inserted will be shoved forward. If you are doing a tri-fold brochure in Word, getting the positions "right" where the text flows into each panel of the brochure will drive you stark starking MAD.

You constantly have to go back and forth through your document and test where things end up.
In Publisher, you lay out the graphics and text blocks as separate graphic elements that are independent of each other. So if you add content to an existing area, at worst it overlaps the next item until you adjust things. But there is no concept of overall text flow of the document, so you aren't modifying the appearance of every other region of your piece when you modify one part of it.
Publisher has many templates, including brochures. I am not certain that Word ships with a tri-fold brochure, but examples are very easy to find on teh intertubes.