I was just visited by my Dell representative who installed a replacement Mother Board for my dell optiplex 740 AMD64 X2 because of a bad floppy drive controller. After she left I discovered my eth0 had disappeared.
The kernel has always recognized it as a Tigon3 (Broadcom BCM5754) It still does in dmesg, but the interface does not come up. From searching I have found 2 suspected drivers for this chip the BNX2 and TIGON3 both are built into the kernel
lspci = 01:00:0 Ethernet controller: Broadcom Corporation NetXtreme BCM5754 Gigabit Ethernet PCI Express (rev 02)
dmesg = eth0 Tigon3 [partno(BCM95754) rev b002 PHY(5787)](PCI Express) 10/100/1000Base-T Ethernet 00:1d:09:02:dd:ee
ifconfig = lo, vmnet1, and vmnet2

I was going to assume bad MB again, however on another partition where Fedora 8 - 64 is installed the interface comes up as eth1 and works fine
I only have the 1 onboard ethernet interface.
I know nothing about Fedora and even though I have been a slacker for many years i don't know much beyond the desktop
can anyone point me in the right direction
Thanks
John

EDIT: after reading about 500 web pages i stumbled upon
ifconfig -a display all interfaces which are currently available, even if down

and lo and behold there was "eth1" never had one of these before
maybe that udev devil changed the name of my interface??
so like a good slacker i vi'ed /etc/rc.d/rc.inet.conf
and changed USE_DHCP[1]=""
to USE_DHCP[1]="yes"
chanted magic phrase /etc/rc.d/rc.inet1 restart
and there it was connected like a good computer

always a fun day when you learn something
Thanks
John

So now what you might want to do is change it from eth1 to eth0 so your not confused. Or this might help you understand as to why this happened.
Okay, in /etc/hal/rules.d/ there should be a rule 75-network- something. I'm not in Linux right now so i may be wrong. Anyways, in that rule, you will see how it is configured to name your eth port on boot. You could change this to eth0 so it makes more sense.

great lesson agent

the file was in /etc/udev/rules.d/75-network-devices.rules
which assigns names per mac address which explains why the name changed with the motherboard change ie new mac address.
this was a big mystery to me, but after examining the above named file it is quite clear

another fun day (2 days 2 new things learned)

Thanks
John

Ha, i always get those 2 mixed up. I don't even know why.

Anyways, glad i was able to point you in the general direction