So I'm giving my 2009 27" iMac to my Mum and Dad as I have a new Retina en-route. I have a few questions for anyone who can help? Whats the best way to "wipe" it but leave certain programmes (Office etc) intact? Shall I just go through photo libraries and delete the files....and I assume for mail - I just need to delete my account and set up a new one for them?? Can I put them on family sharing so they can keep all my music in there etc? Or is there an easier way to do all of this?