Having to purchase two laptops for my College bound kids in the last couple of years. Here's some of the questions I asked the kids to decide on the laptops:
1- What kind of applications you need to run for your school classes. Are they available for Microsoft and Apple Operating Systems?
2- Are you planning to take the laptop to classes to take notes?
3- What kind of games are you going to play with the laptop?
4- Do you plan to watch Movies? DVD or Blue Ray?
5- How much do you want to pay for it? (actually what I wanted to pay for it

)
Laptops are a compromise of weight/size, battery life and performance among many variables.
So here's the selection criteria based on the answers
1- If the apps run only with Microsoft OS's then get a Windows7 laptop. You can set-up the Apple laptops to dual-boot but you need to buy both OS's, learn how to select the OS to boot, etc.
IMHO the Apple laptops are more of a status symbol and a bit overpriced, apps are more expensive and so on.
We saw a student at the College with an Apple laptop and asked her why she chose it. She said that she had 2 laptops, the Apple to take notes and a Dell laptop for her school work since some of the apps run only on Microsoft OS's
2- If your kid is going to take notes with it then select a smaller laptop, no bigger than a 15".
Remember that most school desks don't have much room. My kids do not use it to take notes.
3- If they are playing games then get a laptop with a discreet graphics chip and dedicated graphics memory. and not an integrated graphics controller. Price is lower with the integrated controller.
Some games are ok with the integrated controller but some of them will choke big time.
4- If they are watching movies you probably want to get a wide screen 17" laptop. If they are watching Blue Ray movies then get the Blue Ray drive.
5- Here's you need to insert your price.
Bottom line for my kids was to get them a Dell 17" laptop with dedicated nVidia graphics and a DVD player/CD recorder.
Hope it helps