[ILUG] ldap/PDC

[Nils]

[its a bit OT but read on]
I'll have to replace a windows nt4 domain controller and to allow upward
of 50 - 80 users to be able to user to logon, access fileserver.(all the
stuff you would do on a windows network)
just as a price comparsion i was looking at a dell PowerEdge 1750 with
50 CAL's which come to a total of $5,169.00 exclund vat,the server is
€2,614.00 for the hw alone. 
So what am i asking. 
ok i was thinking that i could go with a Dell PowerEdge SC1425 SATA
 799.00 excluding vat stick debian on it and configure it as a PDC/ldap
auth server.this wont have any shares on it it will just be a Auth
server so i think its ok for that purpose.
Reading the samba howto's on the www.samba.org i'm not really sure how i
should go about doing this,there is a few choices.
http://ar.samba.org/samba/docs/man/Samba-Guide/
If using ldap i was thinking that  i can use it to auth email accounts
instead of having two different systems as it stands now.
At the moment there is a samba file server working already via winbind.
(no shares on the nt4 machine).

A few question.
1. Do i need kerberos.
2. Do i need a dns server/ldap (Active directory) or will a ldap server
work.
3. Is it a good ideas for having the same password for both user logon
to a win box and email account.( i could have two different directory
trees) 

whats the most sane way to set up this, so administration doesn't take a
rocket scientist to understand.
i was looking at something like :
1 http://phpldapadmin.sourceforge.net/
2 http://lam.sourceforge.net/home.htm

As a frontend to add uses,which people could learn.
I think the reason i would take this option is that it has more
flexabililty apart from the inital setup and maintance the cost should
be really a one of cost, unlike the windows route.
I hope i included all the bits of information need for people to
understand what I'm asking.
nils