User Registry Keys Not Displaying?

I have a windows 7 pc and various users who use it. Each user that logs on creates a local profile ok. However when you logon with the admin account and open the registry editor and look under the HKEY_USERS key only the S-1-5-2xxxx entry is there for the admin account and the standard system entries but each key for every user that has logged onto the pc is not displayed.Under windows XP you where able to see entries for all users who had logged onto that pc. Has something changed with Windows 7 by design or is there something wrong with the installation/setup of this machine.