I am not to familar with Mandrake's tools, but I know the lower level ones fairly well.
What do you get when you go:
ifconfig eth0
?
If it returns anything, however if it doesn't have a ip configured with it you can do it manually...
ifconfig eth0 192.168.1.1
or whatever.
Then you set up the default gateway.
route add default gw 192.168.1.254
were 192.168.1.254 = your specific gateway.
If you have dhcp set up on your network you can use programs like dhclient to configure the network...
dhclient eth0
Then make sure that you have dns server in your /etc/resolv.conf
You do it by adding a line similar to:
nameserver 192.168.1.254
Hopefully that will get you going. When you reboot your going to loose your gateway and ipaddress information, though.
If you check out the mandrake forums you will probably find more specific advice on this sort of thing quicker... Probably someone has already had this issue before and figured it out before you. I don't know mandrake's specific stuff for setting up the network scripts other wise I just edit the files manually..