Post the output of /sbin/ifconfig on both machines.
Did you install and configure samba on both machines?
Does /sbin/ifconfig show that both interfaces have IP addresses?
Are both IP addresses different?
Are both IP addresses on different subnets?
You might try using nmap to tell you which ports are open on the hosts.
If you are using the 192.168.1.0/24 network then the route should look like this:
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
The default gateway is what you would use to access a host outside of your subnet--usually a router. If you don't access the internet, and don't have another subnet, then you don't need a default gateway.