First thing you need to do is get access to the following files from the machine that you want to recover the passwords from Firefox from. The files that you need are:

    *  key3.db
    * cert8.db
    * signons*.txt

All of these files can be found inside of the Firefox profile directory usually located in your profile folder under documents and settings. If a master password is set you will need to know that password also firepassword will be unable to decrypt the passwords without it. Fortunately most Firefox users do not know how to or do not ever set a master password for their password manager.

After you have those files you need to download the firepassword binary file from here

http://securityxploded.com/download.php?PHPSESSID=cafc98536a62ccd3453bf5a60cada8d1#firepassword

In case you didn't notice this is a commandline utility. So for most of you GUI Windows users you will need to open it in a command prompt. To do that click on start then run and type in CMD. You should now have a black window. Inside of this window go to the directory where you downloaded the binary utility firepassword.  Now just use the following command:

FirePassword [-m "master password" ]

You can replace the with the directory you copied the previous files.  Now firepassword will generate a text file with all of the decrypted password.  That was easy.