We ripped up the carpet in the loungeroom and hallway and exposed the floor boards. It was an epic to pull the rusted nails and staples out of them before sanding them back. We hired a floor sander with 60 grit paper that whipped through it occasionally sparking up on a nail we'd missed. We then used a hand sander on the corners. Its very important to go with the grain of the boards because going across the boards really stands out. Still not sure what to do with the carpet and foam underlay... it would be a waste to throw it out.