Are you using Network Manager? This has a tenancy of thinking that it knows better than the config files and updateing the resolv.conf file with what it wants. Normally if I am using static addressing I remove Network Manager to avoid issues.
You can update a file dhclient.conf. Depending on what is installed you may have both a /etc/dhcp and /etc/dhcp3 directory both of which will have a dhclient.conf file in it. I am not sure what version of dhcpd Ubuntu 10 has but I would assume that you are likely using the /etc/dhcp/dhclient.conf file.
In the dhclient.conf file add a line like this to override what Node Manger/DHCP is getting:
Or if you want to add you DNS server to the beginning of what Node Manger/DHCP is getting:
supersede domain-name-servers 188.8.131.52
prepend domain-name-servers 184.108.40.206