Bit of a long shot I know, but I'm hoping someone will remember (because Google doesn't!).
There used to be a Windows utility (might have been a shell extension) that added the registry as an item to the Windows Explorer tree in much the same way that the Control Panel appears, ie at the end of the list of drives in the tree pane. This meant you could edit registry keys and entries as though they were folders and files (REG_SZ only I seem to remember). I've googled but no luck; anyone out there with an elephantine memory?