> Is there such a thing as a software ap that runs on a PC which
> can periodically report to a dynamic DNS service

Do you mean such as "dyndnsupd10.zip" from Hobbes:
Description: Updates a dynamic host on dyndns.org

Long Description:
Gets the external IP address, checks it against the given host, and updates dyndns.org if necessary.

Program Contact: David Azarewicz (david@88watts.net)
Upload Date: 2007-07-09
Archive Date:

Program Source: http://www.88watts.net

Al Heath