well, do you have a dhcp server running on your router? iow, does your router automatically give out ip addresses to you? if not then dhclient will not work.
in any case, did you try the other commands i put in my last post? if dhclient doesn't work, the next step is to attempt to configure your ethernet card manually.
(each line is a different command)
ifconfig eth0 192.168.0.2 up
route add default gw 192.168.0.1
echo nameserver 192.168.0.1 > /etc/resolv.conf
if it still doesn't work then you have a problem; in that case i would check the cable and make sure that it works.