The quick change would be to (as root, or with sudo) open /etc/
resolv.conf in the editor of your choice, and change the 'nameserver'
lines, but that change will be lost upon reboot.
To make it persist across reboots, edit your /etc/dhcp3/dhclient.conf,
and look for a line starting with 'option domain-name-servers. If
there is no such line, add it immediately after the 'request' line,
and make it look like this:
option domain-name-servers 8.8.8.8, 8.8.4.4;
Hope this helps!