Buy some felt from a sewing store. You will also need some contact spray adhesive, which you can buy from the hardware store. You will need to follow the directions on the can, but basically spray the contact adhesive on the felt, and on the underside of the chair legs. Leave for a minute then press the two surfaces together. make sure you oversize the felt, then once the contact adhesive has gone off, trim it back to the profile of the leg with a sharp stanley knife. This should stop the chair legs from scratching your floor
Adam, September 2008