Linux Administration - Users in (any) database howto/why...

[kitepilot at kitepilot.com]

OK, I've reached that (long postponed) point of my life where I *HAVE* to 
ditch /etc/passwd and /etc/group in favor of storing my users in a database.
Any database... 

Unless there is a *COMPELLING* reason not to, I will store my users in 
Postgres, but I don't see why generic concepts should not be applied to 
*ANY* database. 

All I find in the howto's is how to install (laundry list here), but what I 
need is a fairly general cookbook about how-to-configure-what to allow my 
machine to validate users contained in my database.
Most of this howto's are useless to my because I run LFS and it right there 
voids any reference to apt-get/yum/rpm/etc. 

Furthermore, I want to login with my trusted  /etc/passwd - /etc/group 
combination when I SSH into (or console) into my machine and I want the 
"other" users (people hosting WEB sites and/or receiving e-mail) be 
authenticated against the Postgres table. 

So the final question is:
What do I need?
specifically, do I need PAM?  (Probably...)
What do I configure? 

I don't need too many details, I just need something along the lines of:
You need this list of packages and you need to edit this configuration files 
to accomplish (fill in the blanks)
Lisa?   :)
HAPPY NEW YEAR!!!
Enrique