Ubuntu Network Interface Issues.
If you are having problems with a new network card showing up on eth2 or eth1, take a look at /etc/iftab. More than likely eth0 (and maybe eth1) are assigned to another MAC address.
Change the MAC address to set the interfaces, or comment out the lines and Ubuntu will assign the interfaces in the order the modules are loaded. Be sure to look in /etc/network/interaces if you change the order of the interfaces.