If you're using a 2.6 kernel, there is a driver included that works with the nforce2 NIC. Try "modprobe forcedeth" as root in terminal.
With the 2.4 kernel, you'll probably need nvidia's drivers. You said the RH driver didn't work, try using the src.rpm. To build do (su to root) "rpmbuild --rebuild filename.src.rpm". In Mandrake, this builds a rpm package in /usr/src/RPM/RPMS/i586/, it's probably similar in Fedora.
The NIC driver is called nvnet. Once the nvidia drivers are installed, do "modprobe nvnet" and set up your LAN as usual