Bree said:
It would be better to leave Administrator alone, for your purposes I would create another local account (say, Admin) make that an administrator and give it a password. Then you can runas Admin rather than the built-in Administrator.
This wonít work. runas isnít designed to run a program elevated, but when you run a program with the builtin Administratorís credentials you guarantee that that program runs elevated due to itís special rights.