Disable login prompt on clients while migrating to outlook 2k3 using Cache mode

We are currently upgrading from Office XP to Office 2003. Are current
settings have the password authentication set to none. So every user
has to login to Outlook. We are setting the new configurations to
migrate existing settings. We had to set a global policy to force
everyone to use cache mode. However, after migrating the accounts are
still requesting for username and password. Does anyone know how to
disable the "Prompt for user name and password" option in Outlook? The
other issue is that when a user see's this screen it wants them to
authenticate to the exchange server instead of the domain, so our users
are getting very confused on how to login. If we can figure out how to
set all accounts to not prompt for passwords are problem would be
solved.

Thanks,
Justin