Cisco 1721 Configuration

Hello All,

I was hoping that someone could help me with my Cisco 1721 Router with a
WIC-1T wan card.

I have read much of the documentation provided through the web site
(http://www.cisco.com/univercd/home/home.htm) however I am still perplexed
as to how to configure the device.

Below is the configuration I require, I am hoping that someone can lead me
in the right direction to configure my device.

1) Allow data to be transferred back and forth between the WIC and the
ethernet port
2) Prevent anyone on the internet (WIC) from modifying the router settings
3) I do not require any NAT or other features.
4) There will be approximately 20 IP addresses allocated from the ISP, these
are to be routed to the Firewall for NAT.

Any help with the above would be greatly appreiciated.

Thanks.
-Steve