Here's a solution to enable the administrator account without the use of a policy editor which isn't available in Windows Vista or Windows 7. This is best to do after a fresh format or when purchasing a new pc.
1. Click START
2. Type: cmd
3. Right click cmd, click Run As Administrator
4. Type: net user administrator /active:yes
5. Press enter
Now log off, log on with the new administrator account. Here you go. Full control, even with UAC enabled. After 1st logon, rename the new admin account to whatever you like. Assign a new password and delete your install account.
Note:
To disable the administrator account again use the following:
net user administrator /active:no