Hi Matt,
I've done all of that again, triple checked all the files are correct, r8168 was in the modules file (shoudl it be r8168.ko maybe). I've ran depmode - a and then modprobe, but it's still failing after about 90 seconds of the boot process.
The actual NIC is an RTL8139, which Foxconn (manufacturer of the motherboard) have given me a link to the r8168-8.025.tar.bz2 download - the one I've installed.
Russell