If you want to explore the SAM registry part, which is only viewable
with the "Local System" account.
One way to gain access to the SAM and Security keys is to execute the
registry.exe in the local system account. PsExec from
http://www.sysinternals.com supports an option that enables you to
launch a process in the local system account.
Download the psexec tool (freeware) from
sysinternals.com and execute
the following command with the help of cmd.exe:
psexec -s -i -d c:\windows\regedit.exe
Then browse to:
HKEY_LOCAL_MACHINE -> SAM
Another way to gain access, is to reset the registry security
settings, but this will waken the system's security!
btw. the "Windows Internals 4th edtion" book has some chapters about
login process and security.