Recently I've come across a couple of vmware images of Debian Linux 4.0 (Etch) where the network didn't work. A call to ifconfig didn't show 'eth0' at all.
I've tried to compare the configuration difference between a successully running Debian Linux 5.0 (Lenny) and these Etch image without success.
I found the solution by chance on a vmware image vendor's web site:
rm /etc/udev/rules.d/z25_persistent-net.rules && reboot