How to Login to Windows XP as the Administrator. If you have failed to setup your Windows XP system with an account that possesses administrator privileges, there are certain tasks that you will not be able to perform. In this case, you must login to Windows using the default Administrator account from the initial login screen. There are a number of ways to do this.
Login in as the Administrator from the main login screen. You can replace the login name on the main login page in Windows if you have Win XP Pro. You delete the login name, retype "Administrator" and enter your Administrator password and login. This option is only available in Safe Mode for Windows XP Home edition.
Press "Control+Alt+Delete" from the main login screen and enter the Administrator password to login in to Windows on Windows XP Pro. The key sequence that you press twice will present the classic login screen for Windows.
Add the Administrator to the login accounts list. Edit the registry to perform this action. Always backup the registry before making any changes to it so that you can recover your system if you make an error. From the Start menu, select "Run." Type "regedit" and open the registry editor. Find the key defined by HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows NT \ CurrentVersion \ Winlogon \ SpecialAccounts \ UserList. Choose File>Export to make a backup of the current key. Create a new DWORD named Administrator. Double-click the new DWORD Administrator and set the value to 1. Exit the registry and restart the computer. The login screen should now show administrator as one of the accounts that can login.