Hi,
You can query the database (there's one db per portal in wss2.0), so something along the lines of of a sql query such as:
SELECT [FullUrl] FROM Sites
Will give you what you want I think. In the registry, you may find the settings for the IIS meta tables but it wouldn't include such items as sub sites, it'll only contain the top level Website details as the WSS info is db centric.
Paul Leigh