Hi Urken, try the following commands :
<your root password"
"modprobe 3c59x" (your network card might be in this module)
Then try to give an ip-adress to your network card, with a command like :
"ifconfig eth0 192.168.1.10 broadcast 192.168.1.255 netmask 255.255.255.0"
See the following URL for more info :
Do you see your network card now, with the command "dmesg |grep -i eth"
Do you see your ethernet device, with the command "/sbin/ifconfig -a".
Note : let me guess... You've got a nVidia nForce2 chipset?
The ethernet card on that chipset might not be supported in the kernel in Slackware 9.0. More specifically, it don't think it is fully supported in any of the recent Linux distributions.
It seems that kernel 2.5.70 is the first one to support this card :
I hope I'm wrong, but these are my initial findings.