So, oops. When I built my Celeron box, I didn't include the driver for my Netgear FA310TX Rev-D1 in the kernel build. The Universal CD automatically detects the network card properly, now I just need to get it configured into my kernel build (using "make menuconfig"). The Universal CD (2005.1) detected and configured it using the Tulip driver (Lite-On 82c168).

So I know it works, I just don't have it right and proper. My original build for this kernel is:

Gentoo 2005.1 Software RAID (part 2) Celeron CPU

During that build, I didn't touch network devices at all. It had automatically selected the RealTek network device driver under the EISA option.

# cd /usr/src/linux
# make menuconfig

(D)evice drivers
--> N(e)tworking support
--> --> N(e)twork device support (should already be BUILT-IN)
--> --> --> (E)thernet (10 or 100Mbit)
--> --> --> --> (T)ulip family network device support
--> --> --> --> --> "(T)ulip" family network device support (turn ON as BUILT-IN)
--> --> --> --> --> --> (D)ECchip Tulip (dc2114x) PCI support (turn ON as BUILT-IN)
--> --> --> --> --> --> --> (I left the sub-options alone)
--> --> --> --> (E)ISA, VLB, PCI and on board controllers (turn OFF)

Now, make sure that /boot is mounted, then compile your new kernel.

# make && make modules_install
# cp arch/i386/boot/bzImage /boot/kernel-2.6.12-Oct2005
# cp System.map /boot/System.map-2.6.12-Oct2005
# cp .config /boot/config-2.6.12-Oct2005
# nano -w /boot/grub/grub.conf

Contents of my grub.conf file:

# Which listing to boot as default. 0 is the first, 1 the second etc.
default 0
timeout 30

# Oct 2005 recompile kernel to add Netgear FA310TX rev D1
title=Gentoo Linux 2.6.12 (Oct 20 2005)
root (hd0,0)
kernel /kernel-2.6.12-Oct2005 root=/dev/md2

# Sep 2005 installation (software RAID, no LVM2)
title=Gentoo Linux 2.6.12 (Sep 22 2005)
root (hd0,0)
kernel /kernel-2.6.12-Sep2005 root=/dev/md2

Not technically difficult, if you can find out what device driver to use. Which, is why I try to document as much of this stuff as possible.