I know these chargers are for (in order) MacBook Pro, MacBook and MacBook Air. Now I'm planning to buy a new one to replace my old broken Magsafe, that worked for my late 2007 white MacBook. I found some sellers on the Internet only have a 85w at really good prices, but I wonder if a 85W will work well on my MacBook. So, what's the difference between a MacBook Pro 85W charger, a 60W MacBook charger or a 45W MacBook Air charger? Will they work on any other Macbooks?