I'm not on 14.04 yet, but it sounds like you set up nopasswdlogin rather than autologin (they are different things)
If things haven't changed too much then you should be able to configure lightdm (which I *think* is used by Xubuntu) for autologin either by editing the lightdm.conf file or by using the lightdm-set-defaults utility
Code:
sudo /usr/lib/lightdm/lightdm-set-defaults --autologin username
See https://wiki.ubuntu.com/LightDM#Autologin