Windows 7 by default disables the remote registry service (probably for security reasons). To enable it from the command line type the following:
sc \\computername config remoteregistry start= auto
make sure you have a space between the = sign and auto
if you're doing this on your local computer you can drop the \\computername part
you can also replace "remoteregistry" with the name of another service to enable or disable it.
once you've enabled the service you can either reboot the computer, or just start it now with:
sc \\computername start remoteregistry
If you want to know why we want to enable this service, it's so that you can pull up the registry of a remote computer that's currently in use (normally hkey_local_machine) via regedit on your local machine. This way you don't have to interrupt whoever is currently at the computer by using RDP, VNC, or kicking the user out of their chair, at most you may have to tell them to reboot their machine at some point.