On the use of pacman -S xfce4, (with everything), I get the following:
resolving dependencies... warning: provider package was selected (freeglut provides glut) looking for inter-conflicts... error: unresolvable package conflicts detected error: failed to prepare transaction (conflicting dependencies) :: xfce4-settings: conflicts with xfce-mcs-manager
Not sure what to do about this... obviously running TWM is no-one's choice for a WM, and XFCE is my preferred.