Apple Order No: MB990LL/A Apple Subfamily: Mid-2009 13" Apple Model No: A1278 These are the specs of the MacBook Pro that I have. Long story short a dog got near the AC adapter cord and had its fun. I need to purchase a new AC adapter and went to Amazon.com to look for one. I noticed there are many different 60W adapters listed for specific MacBooks. I was curious if there was a big difference? Right now I've had to use my ac adapter from my early 2006 MacBook and I haven't noticed any problems. My main question is if it would be OK to buy an ac adapter on Amazon such as: this.