Another Easy method, Using  ophcrack to Hack into Admin Account:
 

Ophcrack is a Windows password cracker based on a time-memory trade-off using rainbow tables. This is a new variant of Hellman's original trade-off, with better performance. It recovers 99.9% of alphanumeric passwords in seconds.

This is a type of offline cracking, Just grab .iso of ophcrack from here. Burn it and enjoy using.

1.  Opchrack can crack passwords for Windows 7, Windows Vista, and Windows XP.
2. Ophcrack can recover 99.9% of passwords from Windows XP, usually in a matter of seconds. Any  14-character or smaller password that uses any combination of numbers, small letters, and capital letters should be crackable.

3.  Ophcrack can recover 99% of passwords from Windows 7 or Windows Vista. A dictionary attack is used in Windows 7 and Vista.

4.  The Ophcrack LiveCD option allows for completely automatic password recovery.

5.  LiveCD method requires no installation in Windows, making it a safe alternative to many other password recovery tools.

6.  No Windows passwords need to be known to use the Ophcrack LiveCD to crack your Windows passwords.

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I think this ophcrack method is far better, Try this one just get a disk and write it, Or else USB disk can aslo be used.

Some security Tips ~ Making strong passwords:
Now, You might have come to know that how passwords can be cracked, So there are some tips for you.
1) Do not make common passwords like 123456 or the one of your own name.
2) Use @, *, # or other symbols in your passwords to ensure maximum security in this case John the ripper and Ophcrack and also other cracking tools may take long time, it will be frustrating for hacker.
3) Keep changing your password. So, that if long time is taken by one hash to decode, until it decodes you have generated another hash.