Dell and HP dont make there own computers
they buy the shells and deck them out themselves same with sony, samsung.
What are you going to do for your school. Are you doing media assignments, involve heavy resources programs.
Alienware isn't an laptop you can around out side your house. Its way to big and overpriced.
And alienware type laptop would be the Asus G53jw-a1, that is an gaming laptop, priced around 1400 USD and will do what you ask.
you got to set out your requirments for example
multitasking: Core i7
Gaming: core i5
media programs: mid range gpu n
gaming: high range gpu
taking away from home: 15" screen max
home pc replacement (get an pc if the case save tonne of money): up to 17"
see thats just an example from me, make your own list of needs then find an laptop your need, and there are alot of places that allow upgrades to laptops which is always good.
Of Course That's Just My Opinion, I Could Be Wrong