Hosting an own website on Windows Home Server is unsupported and may mess up the IIS configuration up to a level, that you need to reinstall WHS. (Also be aware, that using a machine in a home network for hosting a website accessible for Internet users usually
cannot provide the bandwidth needed, if the number of concurrent users is more than a very few, simply because the upload bandwidth of common DSL connections is much lower than the download bandwidth.)
For getting back the same domain name (assuming you are referring to xyz.homeserver.com name) you need to use the same Live ID as you did use for registration. If you used a solution provided by an OEM (i.e. HP) this may be tied to something different or
even be impossible without paying.
Best greetings from Germany
Olaf