resolv.conf gets modified on boot

["Lex McPhail" <lex@ssiltd.co.nz>]

Hi All

I'm a newbie to Linux and trying to setup a firewall / masq system on 
a computer with 2 ethernet cards. I have installed the 2.2.18pre21-
compact kernel.

I modified the resolv.conf file and added our ISP's primary and 
secondary DNS server IP so that the file now looks like:

search <our_domain>.co.nz co.nz
nameserver <ISP.primary.IP.address>
nameserver <ISP.secondary.IP.address>

Ping to an ourside domain name and all is fine but whenever I reboot 
the computer the resolv.conf file gets changed back to:

search <our_domain>.co.nz co.nz
nameserver 192.168.123.1

The IP address is the address I entered when installing the system 
orginally (before I got the second ethernet card working). Where is 
it getting this from and how do I get it to accept the correct 
version of resolv.conf?

I have read through lots of FAQs and HOWTOs but have not been able to 
find the answer.

Thanks

Lex