Authenticating Externally

[Jeff Casimir]

Edubunters,

I'm a high school teacher and Edubuntu-experimenter thanks to Jeff 
Elkner & Kevin Cole.

We've got the default install up and running - the first time you see 
the thin clients come up it is pretty impressive!

Now I want to get fancy.  Our Edubuntu setup is a small "writing lab."  
Outside that lab we have an existing network and many machines that 
authenticate/connect to a central server.

What I would really like to do is have the Edubuntu server "link up" 
somehow with the existing server to authenticate users and, if 
authenticated, mount their network drives.

I'm not a UNIX master and not the admin of the main server.  The main 
server exposes SAMBA services for sure, and I believe exposes PAM.  Can 
either of these be used to do what I want?  What do I call this?  Can 
someone help me get started?

Just in case I'm not explaining it clearly, this is what I'm envisioning:

1) User sits at an Edubuntu thin client and enters their "normal" 
username/password used on the other school machines
2) The client sends the info to the Edubuntu server
3) The Edubuntu server asks the main server if the credentials are valid
4A) If invalid, reject login.
4B) If valid, allow login.
5B) Mount user's SAMBA drive from the main server onto the client session

Possible?  Insanely complicated?  Trivial?

Thanks for your time,
Jeff