How to enter Windows XP when you forget the administrator password?

PR Log (Press Release) – Jun 26, 2009 – OK, you say you have forgotten the Windows XP administrator’s password and can’t log on the system. Oh, well, it is not that scary as it seems and is really with solutions indeed. Then how to get out of the situation without reformatting and re-installing the operating system?
Well, Microsoft has offered many helpful tips and tricks on their help center, which you can refer to. At the same time, I will offer you several methods that may be of help.
Method1. Get a bootable floppy disk ready
Windows system has provided us with a function to create floppy disk for password recovery. In case the password is forgotten, we can boot the computer through the floppy disk. Then how to create the floppy disk with the provided function? Click “Start>Control Panel>User Account”, in the pop-up window, choose your account and click it, and you are led to the “User Account” window. Select “Prevent a Forgotten Password” on the top left corner, and you are navigated to the “Password Forgotten” wizard. Click “Next”, and a tip will pop up telling you to insert a blank formatted floppy disk to the floppy drive. Then click “Next” and input the current account password based on the instructions. The creation takes only several seconds. In case the password is forgotten some day, we can simply insert the ready floppy disk into the floppy drive. Click the arrow on the right of the user account, click “Use Password Recovery Disk” in the pop-up window, then follow the instructions to reset the password and enter Windows. This method is applicable to Windows XP of any kind of partitions.
Method2. Delete the password with another operating system
If the computer is installed with other operating system, then boot the computer through the system, delete the “SAM” under “C:WindowsSystem32Comfig” directory (provided Windows XP is installed in the hard drive C), which is the database file of account passwords and reboot the computer. Then the administrator account password of Windows XP is removed. Similarly, if there is only one Windows XP system, you can just remove the hard disk to other machines and delete the “SAM” file.
This method is applicable to Windows XP installed on FAT 32 partition. If Windows XP is installed on the NTFS partition, then make sure that the system can visit the NTFS partition.
Method3. Use NTFS DOS tool to restore Windows XP password
First of all, download a "NTFS DOS" tool via which to create a bootable disk that can operate NTFS partition under DOS. After the DOS is started, switch to system directory, e.g. “C: WindowsSystem 32”.  Change the name “Logon.scr” with “Logon.scr.bak”. Get a copy of “Command.com”, and rename it with “Logon.scr”, then reboot the computer. When the screensaver is activated, you will see that the screen is shown in command-line mode with administrator permission, with which to reset the password or create new administrator account. After you log onto Windows XP, rename the “Logon.scr.bak” back to “Logon.scr” will be OK. This method is applicable to the Windows XP installed on NTFS partition.  
Method4. Use software programs.
If you are not a computer technician, or not familiar with computer system operations, you may feel the above methods are scary and still can’t figure out what I am saying. Then you may try to use the software programs which may suit you. The existing software that used to recover passwords are many.  Windows Password Reset 6.0(http://www.windowspasswordreset.com)  and windows password unlocker 4.0 (http://www.passwordunlocker.com)are mostly used by people. It’s easy-to-use little tools that people like. The program do not require professional knowledge. You just follow the instructions to click mouse or press keys will be OK. Plus, It also works with other versions of Windows, like Windows Vista/2000/NT workstations (including Windows XP Tablet PC Edition).