I don't seem to have a display-manager.service in F18.
It's there in F17 supplied by systemd.
But "yum whatprovides */display-manager.service"
gives no result in F18
I can only get X with startx or startxfce4
KVM VM with Xfce4, lightdm.
systemd-188-3.fc18
ditto rawhide.
--
Regards,
Frank
"Jack of all, fubars"