This is what's confusing to me. The difference between a domain and a workgroup is actually a very fine line. In fact a domain is nothing more than a workgroup with the ability to form special security agreements between machines and a centralized database of user accounts.
Win 9x/Me, for example, can participate in a domain, but it couldn't "join" the domain. That is, it can access domain resources as long as the user provids a valid username and password.
I can't see why M$ would go backwards and make Win XP home even more archaic than Win 9x by removing the ability for it to even see a domain. Actually, I'm 99% sure that if Win XP home can't see a domain, then is wouldn't be able to see a typical Windows workgroup. Again, I have no expereince with Win XP so maybe I have no idea what I'm talking about.
Greg