I've got a 2nd gen Macbook Air and I recently purchased the OSx upgrade and installed it under my Apple account. My wife is getting me a new Air and I'd like to sell the old one and figured it would be worth a bit more if I advertised it as having the latest OSx. Now how do I transfer ownership of this OS upgrade to the new owner? I don't want to give him my username/password in case he ever needs to redownload it. Anyone know of a way to transfer this to the new owner?