If you are worried about the passwords did you securely delete all your other files, deleted items, cache etc?
It's trival to recover items that have just been deleted using normal methods.
It is usually good practice to completely wipe a drive with a disk eraser tool as even formatting a drive does not destroy the data.
There are many stories of "interesting" material being recovered from drives bought second hand.
http://www.theregister.co.uk/2005/02...rd_drive_data/
http://www.channelregister.co.uk/200..._sold_on_ebay/