The institution we support has licenses for Vista Enterprise and we want to upgrade several users from Vista Home Basic and Vista Home Premium to Vista Enterprise. Unfortunately, this does not seem to be an option except to perform a clean install and wipe out the current install which is not a viable option for our users since we want to preserve their application installs. All we want to do is join these machines to our enterprise AD domain, but are unable to. Are we at an impasse? Is our only option to purchase Windows Vista Ultimate retail licenses and/or perform clean installs of Vista Enterprise?