Here's how I have done it.
Go to the NVidia site and get the driver set for NVidia/Linux. Untar/gzip it into a directory somewhere. cd down to the nvnet subdirectory and build those files. then copy ONLY the nvnet.o into your /lib/modules/2.4.26/kernel/drivers/net directory. (be sure to gzip the nvnet.o file, once it is there.)
Next reboot, your modprobe.conf and modprobe.conf may get refreshed during the bootup. Your module listing (lsmod) should show nvnet. if you have dhcpcd enabled, you should have an ip addy and netmask.
Here is my resulting ifconfig: (I am on an ASUS A7N8X-Delux, with both a 3COM and an NForce2 built-in network interfaces. the 192.168.1.3 is the NForce2)
eth0 Link encap:Ethernet HWaddr 00:E0:18:F1
8:E0
inet addr:192.168.1.2 Bcast:192.168.1.31 Mask:255.255.255.224
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:8292 errors:0 dropped:0 overruns:1 frame:0
TX packets:9992 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:8387766 (7.9 Mb) TX bytes:700795 (684.3 Kb)
Interrupt:11 Base address:0xc000
eth1 Link encap:Ethernet HWaddr 00:0C:6E:02:3C:EA
inet addr:192.168.1.3 Bcast:192.168.1.31 Mask:255.255.255.224
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:447 errors:0 dropped:0 overruns:0 frame:0
TX packets:416 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:224932 (219.6 Kb) TX bytes:69335 (67.7 Kb)
Interrupt:5 Base address:0x6000
HuMJohn