Recover HD from iMac

My in-laws imac has been crashing for a while now. I told them to backup 30 times or more. Anyway needless to say i think they understand now. The HD has crashed and they can no longer boot into windows. An apple repair shop said it's not possible to get the data back without paying 900 to send it to a special facility.

So I booted up a new Ubuntu 14.04 live CD and started up gparted. As it's scanning for drives it pops up a message reading "The journal is not empty. Parted must replay the transactions before opening the file system. This will modify the file system." As I am trying to get their data back in tact I want to make sure that I am not causing irreparable damage to the drive.

So I did some reading and people have mentioned needing to turn off journaling in the mac os first as this isn't possible at this point what do I need to do? Is it ok to replay the journal and get their unsaved data? Or should I try removing the HD from the machine and put it into another system? I would much prefer to keep the system in tact if possible.

Thanks in advance. I am not super familiar with Mac although I am a long time CentOS and Fedora fan. I have also used Ubuntu back in the 10.04 days.

Thanks,
-Matt