The LDAP Server root settings do not show up in server-manager on my 6b3 test server either however the dc settings are only your server domain name.
example 1
If your domain is foobar.com then dc=foobar,dc=com
example 2
If your domain is foo.bar.net then dc=foo,dc-bar,dc=net
I just tested these settings using Outlook 2000 on a Win2K Pro machine against my SME 6b3 test server with the latest updates.