My PC is going to a new home, complete with it's two HD's and two SSD's. Normally, I would destroy disks to ensure my data was unreadable but this time they are remaining intact and will go to the new owner (family member) as a fully working machine, Windows 7 installed. He will be taking it to Aussie and will potentially need to grant access at the border.
Sooo... I need to remove all my data and santise the disks. I've recovered data from formatted disks myself so am aware that deleting, overwriting, and reformatting before reinstalling Windows is not enough to ensure my data has completely gone. Never having done this before, I need some advice on how to remove all traces of me from these drives. I contemplated destroying the drives and replacing with new but this is money I can't afford (and it seems a waste when the drives are relatively newish). Any tips on how to santise please?