The Wiki has some notes on netbooting, under a variety of nodes.
http://www.wlug.org.nz/NFSRoot
is probably a good one to start at.
A quick check of the config file for Debian 3.0's 2.4 kernel (2.4.18-bf2.4) shows that it doesn't have CONFIG_ROOT_NFS set, so I guess that's the current problem. As the page also says, your kernel options as above are right, but it might pay to set ip=dhcp as well.
Once you get nfsroot support into the kernel, you also need to tell it that it's root is an nfs device (the root=/dev/nfs you had) and where to mount the root. So, you need a kernel command line something like the following: root=/dev/nfs nfsroot=<server ip>:<root filesystem export point> ip=dhcp The ip=dhcp tells the kernel to get it's IP address via dhcp, not bootp or something else. You will also need to make sure that you have "kernel level autoconfiguration" (or something similar) set in the kernel build as well as compiling your network card driver into the kernel, not as a module (or, you have to muck around with initrd's as well !). Jamie