Windows

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If your users are using W2k or Xp they already have to login. To login into your server set it up as a domain controller then craete a domain for your users to log on to.

or Upgrade to Windows Server 2003, easer to manage and you also get Windows Sharepoint Services (WSS) for free.

Configure a domain to your network.
The server must be the DNS, and all the computers must set to use this DNS.
This mean, you first time configure the server, after go to each computer and set the workgroup, and DNS server. You can do this from right click on My Computer, select Properties, Computer name, Change and activate the radio button Member of Domain, and enter the domain name what you set on server. After this right click on Start menu->Settings->Network Connections->Local area Connection, select Properties, from menu what appear Internet protocol(TCP/IP) -> Properties and activate the radio button of Use the following DNS server address, and in Preferred DNS server write the server?s IP Address.

I would keep AD domains as you only need to create logins once and not on every server and workstation.
To get users to map drives automatically, you can use login scripts to map drives for them, it would easier to set in a domain otherwise you need to create a script for every single user....

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