This probably depends on your distro, but for my Red Hat box you want to edit the file in :
/etc/sysconfig/network-scripts
called "ifcfg-eth1" and make it so it reads:
DEVICE=eth1
BOOTPROTO=static
IPADDR=192.168.0.1
NETMASK=255.255.255.0
ONBOOT=yes
That should work for you, it should bring the device up on boot, and assign it that address,
Hope this helps.