newbie question

[Peter Duda]

I am setting up a domain in a small office with all windows computers.  I
have configured a linux box to run and administer the domain.  I also have a
web based system that I would like to run on this domain.  This system would
and should only be seen on the intranet - nowhere else.  Here is my
question.  I have neither the knowledge nor time right now to learn and
configure DNS on the broad scale.  I would like to set up BIND so that
mydomain.com is resolved by all my local computers and leave the rest of DNS
to those nice and handy numbers that my ISP provides.  What is the easiest
and best way to accomplish this task, and where can I find help in
accomplishing that?  Do I set up BIND to serve up the local domain and
somehow point BIND to the other DNS servers - do I do that through DHCP - do
I do it through the client computers?  I don't wish to slow down normal web
traffic by having it query my server for every single web page that is
served to my computers.  Does that matter?  I apologize for the remedial
nature of this question, but I have spent a few hours scouring the internet
for this answer and everything I read is a long treatise on the proper way
to set up BIND for hosting a web site and resolving all names, and this and
that and my head is now spinning . . .

TIA 
Peter