Thank you for the answer...My registrar prompts me for a second ns.
So far I have been using a dyndns service, but now I want to do my own.
Very broadly speaking I guess I can do as follows:
1) Install 2 computers running Linux Ubuntu server 10.04 (with bind installed on both)
2) Connect them to a switch connected to a broadband (fiber) converter and then make one of the computers be ns1 and the other ns2 right?