Yes,, you would be surprised what is on an HDD even AFTER a format!
WHat you need is a disc scavenging application...a file recovery software,,
Search for Hard Drive recovery,, or Scavenger,,
cheers,,
PS,, If you wish to capture conversations of others through instant messengers,, then I would suggest a Keylogger application,, You got a Fox in the henhouse ??
cheers,