Do a few tests. When the computer first boots up, open a terminal and become root.
Run command: ifconfig
If you see eth0, run command: dhcpcd eth0
If you do not see eth0, run command: ifconfig eth0 up
then run: dhcpcd eth0
When you figure out what it takes to activate the network card, you can add those commands to the end of /etc/rc.d/rc.local