Hi,
I've just read the first advise and I'ts just what someone has to do in case of loosing root access. Very keen, but in case of a device missfunction you can try this. But you must have root access.
In case of a red hat box, sometimes linuxconf and kudzu do not place the right dirver and you need to find out if a PCI NE200 can be placed in stead.
send a ping at the net card. i.e
ping 192.168.20.20
if it's alive the net card will answer
at the command line type
ifconfig (command with no flags)
ifconfig displays netcard status and configurations.
see man ifconfig
good luck !