[CentOS] Trying to create a custom initrd that will work with PXE Booting

Hi,

I am trying to create a custom initrd that will work with PXE Booting on 
CentOS release 4.5 (Final) and Fedora Core 6.  Can anyone point me to 
some documentation that will help with this ?

The specific situation is that we have received some machines that need 
the latest e1000 Driver from Intel in order to detect the network card.  
If I install the systems without network and then do rpmbuild -tb 
e1000-7.6.9.tar.gz a RPM is built and can be installed, and the Network 
card works fine as soon as you load the new e1000 Module.  But we could 
be receiving a number of these systems so a Kickstart installation is 
required.

I have tried installing the version of the kernel uses during kick start 
installs and then creating and installing the e1000 rpm and then 
updating the pxe initrd with the version of e1000.ko that is created but 
still the the card isn't detected.

Another thing I have tried is creating a respin using Pungi and then 
using the PXE images that this generates but still no joy.

I do know that the Card works fine with CentOS 5 and Fedora 7.  Aside 
from upgrading to these does anyone have any suggestions? :)

Thanks