xubuntu-system-tools conflicts gnome-system-tools, but xubuntu-desktop depends on x-s-t | g-s-t. So if x-s-t is installed when installing g-s-t, x-s-t will be replaced by g-s-t without removing xubuntu-desktop (hm, am I clear?).
What exactly did you try to do? I've just installed xubuntu-desktop then ubuntu-desktop and everything works fine. ** Changed in: xubuntu-system-tools (Ubuntu) Status: Unconfirmed => Needs Info -- conflicts with gnome-system-tools https://launchpad.net/bugs/56370 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs