Hide this server from prying eyes

I have a w2k server which houses my email software…while I have killed access by not sharing any drives, ideally I would like to hide it from the network entirely…however under network identification there are radio buttons for workgroup or domain…we are simple folks and have no domains to require logging…bottom line is…I don’t want users even to know that the sytem exists to be dorked with…How can I hide it entirely?