I am attempting to Impersonate an administrator account from a LocalSystem Service in order to get data from administrators HKEY CURRENT USER registry - in order to impersonate
Everything I've read on the subject seems to indicate that impersonation should get you access to the HKEY_CurrentUser for the impersonated account. However, it could be a quirk in the .NET Registry implementation.
This is just a hunch, and an untested one at that, but have you considered using Registry.Users instead of Registry.CurrentUser?
You'll need to find the SID for the Administrator account, but you should be able to deduce that using Regedit