Exchange 2000 e-mail accounts

I'm a Network admin at a Community College. We have exchange 2000 running and are about to start giving students their own e-mail accounts which we want them to access through the web. How do you create e-mail accounts for them without giving themaccess to use their accounts to log on to the computers on the network? We have active directory running on our Win 2K servers. Thanks a bunch in advance.