So I'm about to buy a used 15" Macbook Pro from craigslist. The seller upgraded the HD and RAM and and said that the Applecare is good until Feb. 2012. My question is do these upgrades void the applecare warranty? I ask because some warranties are void if you open up the computer or break the manufacturer's seal. Also, is Applecare transferable? He said it is under his name but if there was ever any problem they would use the computer serial number.