I'm not sure what you are looking for. If you want to centralize
administration you need to look into NFS and NIS or alternatively DNS
and LDAP. NFS and NIS are the linux defaults for Linux but DNS/LDAP
will allow you perform administration acrossed Windows clients/servers
also. I've got NFS and NIS figured out but am still working on DNS and
LDAP. These arrangements will work fine though with your login screen as
it currently stands. Samba can also be used to set up file and printer
shares that are somewhat interchangeable with M$.

Now, are you just looking for the graphical login? That is easier to
change. All you need to do is change the default runlevel to 5. You
can find this in the file /etc/inittab