Two NICs in Single BOX and two separate network connection handling

List,

Can some one shed some light on this?

I have a server  box  with two interface cards.  I want to use the scenario
like this

1.  First NIC  card should be attached to a WAN link which will handle all
the internet traffic to and fro to  this machine.

2.  Second, NIC will handle all my internal   LAN network traffic where
this machine is connected to my  Local Area Network.

Q1:  What are the configurations I need to make in the two NIC cards to
achieve the requirement specified in   1 and 2.

Q2. What will be the  gateway configurations  needed to add to achieve
these two use cases in a single box?

Any hints most welcome

Thank you.
Krish