If you can find the old Outlook Express folder inside of the old Program Files - great. Copy everything there and paste it into the new Outlook Express; there will be some grumbling about overwriting - do it. That'll bring back your address book.
The mail is another matter. That folder has a Registry type name - very long & alphanumeric. It's the Store folder which can be accessed under Tools - Options - Maintenance. I doubt if you ever looked; right?
Well, all the mail folders have a .dbx extension. Perhaps a Search will uncover them in the old location. If you locate them, you can go to File - Import - Messages (in the new OE) and bring them in. Those you can't just copy into the OE folder.