merging the exchange 5.5 and 2000 global

hi friends
i want to ask u one question i will explain here
i have two exchange servers one is 5.5version and one is 2000 server,and its in same network and with interconnected with routers,these 2 are for different domains,i need to get globel adress list from both server for both clients i think u understood,so what i have to do get this in our outlook 2000,so clients can send email from accesing adress book ,please suggest me one solution.
if some one knows how to configure auto responder in exchange 2000 without any third party utility please mail me the steps or scripts

hrishi