[jabulon]

For DVD authoring (with no conversion/encoding needed) and assuming you don't want fancy scrolling menu's etc I would advice DVD Styler (to begin with). It is pretty simple, straightforward and easy to use (there is a manual online). The only annoying thing is that the installation contains adware like browser toolbar addons, new start homepage, software suggestions (nothing that can't be undone). If your friend feels comfortable with it he can always scale up.