If your administrator account is password protected, then so is the administrator account in safe mode. They are one and the same.
If the user's account is enabled, and has administrative priveledges then the Administrator account will be hidden from the welcome screen.
When you install Windows XP Home Edition, you are prompted to enter a password for the Administrator account. After the installation has completed, you can only use the Administrator account in Safe mode. When you use the Administrator account to log on to the computer in Normal mode, you may receive the following error message:Unable to Log You on because of an Account Restriction
This issue occurs because the Administrator account has been set aside so that it can be used in Safe mode when the Owner account is not available.
This behavior is by design.
To change the password for the Administrator account:
1.Click Start, click Turn Off Computer, and then click Restart.
2.After the computer completes the Power On Self Test (POST), press F8, and then click Safe mode.
NOTE: If you have difficulty getting to the Safe mode menu command, press F8 repeatedly after you turn on the computer.
3.Log on as an Administrator, or with another account that has Administrator permissions.
4.Click Start, click Settings, click Control Panel, and then click User Accounts.
5.Click the Administrator icon.
6.Click Create a Password or Change my password.
7.Type a password for the account, and then retype the password to confirm it.
8.Type a hint to help you remember the password in the event that you forget it.
9.Click Create Password or Change Password.
Since you want to password protect your system, please keep this article