prob with broadband router

we currently use windows 2000 server in our lan with xp as our o.s. of workstation. we use winproxy as our internet sharing. we purchaseda broadband router to replace the winproxy to share the internet but the problem is the broadband router is try to change the dns of our client workstation to the dns of the router. i have my own dns server locally (192.168.100.1)same with the ip address of our 2000 server. how can i share the internet without affecting our local lan…thanks