I received AppleCare on one of my machines, and it is being returned due to a defect. Do I have to get a new AppleCare warranty or can I just use the one they sent me? They sent me a CD, an AppleCare Protection PLan Certificate (with part No., hardware serial no. and coverage end date.) Can I sell this warranty myself? I read that some are being sold on ebay. Is it legal to sell your warranty?