eth0 fails

[Jason Pinkney]

Hi,
I just installed FC5 on a Dell PC. 
When it boots up, it fails to find an
IP address for eth0, even though it is
connected to the network via ethernet cable.
Once it is booted, I can start up the same
eth0 device easily (using e.g., the Network
Device Control gui).  The device specifies
to use DHCP rather than explicitly defining
netmasks and such.
How can I get the eth0 to start during
boot?   (Where could the problem be?)
thanks,
Jason