Hi, I want an extra power adapter for my MacBook Pro 15". That way I can leave one at home and travel with one. You know, the normal situation. However, I am reading horror stories about the power adapter (fraying, etc.). But then I saw that Apple pulled those adapters and replaced them (maybe) with a better version. Basically, which adapter should I buy and where should I buy it from? Does the Apple store / MacMall have the newest adapters that don't fray or am I confused about something? Thanks.