The driver for the network card is probably not loaded. Do you happen to know the type of network card you have and what linux driver it uses? If you post the brand, I may be able to tell you a driver to try.

For example, I have an nvidia nforce2 network card that uses the "forcedeth" driver. To get networking up, I can load the driver with:
Code:
modprobe forcedeth
Once the driver is loaded, I can use:
Code:
netcardconfig
to set up networking.

If that doesn't work, there are a couple of programs included that do automatic hardware detection and setup. One is "kudzu" developed by RedHat. You can run it from the command line using the command "kudzu" as root. If Kudzu detects your network card, I think it will tell you what driver it uses. The other program is "hwsetup" from Knoppix. Hwsetup is what runs when you see the green bar during boot up from the CD. You can run that using the command "hwsetup" as root from a terminal. After running one of these programs, you can re-try "netcardconfig" to see if it works. Once you know what driver needs to be loaded, you should add the name of that driver to the file /etc/modules so that it is automatically loaded at boot up. Good luck!