Network Card replacement
DEVICE=eth1 BOOTPROTO=dhcp HWADDR=00:08:74:46:D7:E5 ONBOOT=yes DHCP_HOSTNAME=delllap.jesnet TYPE=Ethernet
You can find details of all possible configurations in the CentOS manual.
Then restart the network service. service network restart.
If the interface names are not coming up correctly, you might want to update the
/etc/udev/rules.d/70-persistent-net.rules
Refer to http://www.linuxfromscratch.org/blfs/view/development/chapter07/network.html
Further reading (just in case) : http://jeeva.us/Linux/Network