Windows Vista has an inbuilt administrator account that, by default, is disabled and hidden (much like XP), but unlike XP, this account is a true super user account (equivalent to root in Unix/Linux). A simple benefit of having such an administrator account like this is that it is not subjected to User Access Control (UAC) restriction.
Enabling the Administrator Account and Showing it on Welcome Screen
To enable the admin account and then show it on the Vista welcome screen do the following:
1. Logon to Windows Vista with normal user account username and password (with administrator status).
2. Click on Vista Start button, and type cmd in the Start Search box.
3. Right click on the returned result, and then select Run as Administrator.
4. In the Command Prompt window that opens up, type the following text in the command line to set a password for administrator account. (If you want to use a blank password for the Administrator account, skip this step.)
net user administrator <password>
5. Press Enter. (Note: If your computer is a member of domain controller or has enabled complex password requirement in Local Security Policy, you will have to pick a really hard-to-remember password mixed with symbols.)
6. Next type the following command and press Enter to activate and enable Administrator account:
net user administrator activate:yes
7. The process should be completed with the following message:
The command completed successfully
If success message is not displayed, then repeat the process again.
8. Logout from Vista by choosing Log Off or Switch User.
9. Click on Administrator icon and logon with the password you selected.
There is another way of enabling the Vista Administrator account using Graphic User Interface (GUI).