I wonder if it is due to Windows Authentication on OWA and XPHome not supporting some of the normal authentication methods (like domain membership)???
I have an idea, but it involves whoever is responsible for the Exchange server making a change toit. If possible, have OWA set up for not only Windows Authentication (the login/password box that comes up when you connect to OWA), but have it also set for Basic Authentication.
Then try and connect with XPHome.
Basic authentication would allow you to use the same login/password you use from the XPPro machine, but you must remember: it is NOT secured! Basic authentication goes over the Internet in CLEAR TEXT! If someone were running a sniffer where they could get the packets you are sending to the Exchange server, they could easily get your login and password.
But, it might take care of this OWA login problem with XPHome.
I really hate XPHome!
Good luck