dial-up connection into NT network

We have an Exchange Server which has Remote Access Services installed on it. We have remote clients that are dialing into the Exchange Server to reach our network and gain access to other resources on it, such as shared files and databases. Each of these clients have the proper permissions for dial-in, but when they connect, they can’t see past the Exchange Server. They can’t view any of the workstations on the network. The particular client is using Win2000 prof. Please advise on a solution or help me with this. Thanks in advance.