How can I setup a Linux firewall router for my public class C IP block?

My ISP has given me a T1 line with the IP's
69.25.19.0/24
69.25.19.0 Network
69.25.19.1 Gateway
69.25.19.255 Broadcast

I have a server with 2 nic cards, 1 nic card has my t1 line, the other has a cat 5 going to my switch, and I want to set it up to handle all the traffic and filter it with IPtables. How can I route all traffic through that server?

I know I have to run:
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -P FORWARD ACCEPT
iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to ?????

What do I make the IP's of my 2 nic cards? What do I use as the gateway of my server with the 2 nics? What do my servers on the switch use for the gateway?

Thanks in advance.

Do you want systems behind the firewall to have IPs from your class C, or from a private address block, like 10.0.0.0/8, or 192.168.0.0/16?

I am wanting them to have IP's from my class C block.

Ok, then you don't want to do any natting. In fact, you should just be able to activate ip_forward, set the FORWARD chain to ACCEPT and they'll be online. You can then tighten down your security.

So I just run these:
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -P FORWARD ACCEPT

What would I set the IP for eth0 and eth1?

What default gateway does the router server need? What default gateway should the other servers have?

Assign eth0 and eth1 an IP from your class C. Set your clients to use the server as the gateway. Set your server to use your ISP's gateway.

Is there any way to keep my ISP's gateway for the "clients"? I already have a few "clients" active using the ISP's gateway

Realistically, with it not being NAT, that might work as well. Give it a try.

How can I get it to just forward all out bound traffic without filtering it at all?

Should do it