Ophcrack  is a free Windows password cracker based on rainbow tables. It is a very efficient implementation of rainbow tables done by the inventors of the method. It comes with a Graphical User Interface and runs on multiple platforms. Not even a password cracker but also helps to RETRIEVE password from our system.

FEATURES:

• Runs on Windows, Linux/Unix, Mac OS X, ...
• Free and open source software (GPL).
• Real-time graphs to analyze the passwords 

DOWNLOAD OPHCRACK:     ophcrack  
 
CREATING A BOOTABLE FLASH DRIVE:
    For this you will be needing a software which can make your flash/usb drive bootable,
UNIVERSAL USB INSTALLER, a free version can be download from here UNIUSB 

1. First download the Ophcrack XP Live CD ISO form the above link.
2. insert your usb/flash drive
3. download and run universal usb installer, select the ophcrack vista/7 from drop down menu
4. select the ophcrack file, from where u have saved it in your system, then follow the instruction giving proper space(according to your convenience) .
5. Create a folder named vista_free inside the tables folder on your usb flash drive
6. Download and unzip the tables_vista_free. zip to the tables/vista_free folder on your USB Flash Drive.
7. Reboot your PC and set your system to boot from the usb drive.

hope u all will enjoy this. enjoy !!!!! :D