Service Packs via Active Directory

We've run installs with the Admin Director for 2006 with success, however, they required admin privileges at each workstation...as did each service pack. So we still needed to touch every machine by hand. For 2007, we ran the initial install via Active Directory without any trouble (no intervention required). Unfortunately, we haven't been able to successfully force SP's to update the client installs.

Has anyone been doing this successfully, and if so, how? Redeploying the policy after the image is updated doesn't seem to work, nor does adding a package to the policy to update the first package. Any suggestions would be appreciated.

Thanks