Fedora Networking :: Why Primary Interface Is Eth1 Instead Of Eth0?

I have two network interfaces on my computer but only one of them is connected to an Ethernet cable. Until now on every Fedora release, the activated primary interface has been named as eth0 and everything has always worked well without any problem. Recently I switched to Fedora Core 12 and surprisingly I observed that for the first time, my primary interface has been considered by the system to be eth1 instead of eth0. I tried to replace the content of ifcfg-eth0 by ifcfg-eth1, yet system gave me an error that there was MAC address mismatching. I conserved their MAC addresses in their files and just replaced other connection parameters ( such as IP ADDR, NETWORK, NETMASK, etc.) but it did't work. When I do "server network restart", the command blocks.

As I try to install oracle on this system, regarding the fact that oracle requires static network configuration on the primary network interface, I don't know how to proceed in order to set eth0 as my primary interface (or rather set the current eth1 to eth0 because it is actually eth1 that refers to my activated primary network card).Just one more time, I would like to remark, that with previous versions of the Fedora Core, on the same computer (with the very same two network cards) I never had problem and I had installed oracle on the system with success, having the statically configured eth0 correctly detected by the system.