pludi is correct, determining MD5 salt could be based on several things, timestamp that the user was created, last password change, you name it. Determining password is a pain in the butt, you could get some crack utilities like John the Ripper. But if you are the sysadmin of the box, reset the password, or force a password change for the end user.

Being security conscious I don't want a file laying around with passwords in an unencrypted format.. Get a trojan horse have that file stolen and kiss your career goodbye.