Remote registry and Vista
In order to remotely manage and patch Vista, you need to tweak and reenable the remote registry service.
To do this via group policy, build a policy that turns it on like this:
The group policy setting is under computer configuration, Windows settings,
Security settings, System services.
Scroll to "remote registry", define policy setting, choose to make it
automatic.
Voila.
You'll need to do the same for Win7
Read the complete post at http://msmvps.com/blogs/bradley/archive/2009/02/23/remote-registry-and-vista.aspx