If you have Windows XP or Windows 98 in your PC with Fedora Core ,then go to Win and see the hardware manager .Search for the name of the ethernet card.Find a suitable driver from the net.Install the driver in Fedora Core 6.So,your ethernet card is ready.....njoy the net.
In case of INTEL 945GCNL Its
Realtek
RTL8168/8111
To download the driver click here.