They're crappy indeed, but the trick with udev worked. I made a file in /etc/udev/rules.d with the name "ethernet.rules". In it I have the following two lines:
KERNEL=="eth*", SYSFS{address}=="00:50:da:4f:11:51", NAME="eth0"
KERNEL=="eth*", SYSFS{address}!="00:50:da:4f:11:51", NAME="eth1"
This works because I only have two ethernet interfaces in the machine. One, eth0, is always correctly identified. The other has a mac address which is different from the first one and will be called eth1.
I rebooted and lo and behold the whole house had internet access through the core. I was able to install orbiters on my other PC's and control everything connected to the core. Tomorrow I'll try remote booting a MD.
Guys, thanx a lot for the quick assistance. It saved a bundle of time. Once I'm done with the setup I will create a description of the whole process in the wiki.