I have managed to get over most of my connection issues. These were down to a combination of DNS configuration problems, and firewall issues.
The DNS problems stemmed from the fact that there were "allow-query" and "listen-on" entries in the /etc/named.conf file that effectively restricted queries to the localhost. So, for example, dig @localhost riverside.forensit.com would work, but using the IP address dig @192.168.2.8 riverside.forensit.com would fail. My guess is that these entries were written to the file when I was messing around with system-config-bind, although I don't recall changing anything.
After fixing the DNS problems, I installed Firestarter. I might have been able to get away with Fedora's own system-config-firewall, but I'm familiar with Firestarter - and it logs blocked connections so you can easily see what is going on. Once I'd opened up the Samba, DNS, LDAP and HTTP ports - not forgetting the Fedora Management Console port, I was starting to get somewhere. I was still unable to see my "Riverside" domain on the network, however. I couldn't see it from a Windows machine, and I couldn't even see it from "Network" on the server itself.
Being able to browse for the domain on the network is dependent on the Samba nmbd daemon (that's service for the Windows-minded.) nmbd is controlled by the line
wins support = yes
in the /etc/samba/smb.conf file. You would think then, that when you started Samba, nmbd would automatically be started too. Well I did. It wasn't. I manually started "nmb" via system-config-services and "Riverside" appeared under "Microsoft Windows Network" on my XP machine.
Almost there? Unfortunately there is still something missing. Although I can "see" the domain, I cannot get a Windows machine to join the domain. There's still more work to do.