one server with two ip address

[Ray]

Hello all,
I have a production server with two network interfaces.  The primary interface 
is up and running. (DHCP from the local Telco) The second interface is 
installed, but not yet active. It will run on a local network only. Can I do 
something as simple as 
ifconfig  nfe1 192.168.0.100
to give myself access to the internal network? As this is a production server, 
I don't want to just play with it too much.  
Thanks,
Ray