What laptop should I buy for school?

As you may know by the title, I'm in the market for a laptop for school (and minecraft) let me tell you what I need

I will be attending my senior year next year (when summer break is over)
After that I will go to college for mechanical engineering, so I figured I better get a laptop now.

Also, I want to be able to play mine craft mod packs, like the big ones with high framerate

So anyway, here is what I can get:

Alienware 18 ($2099)

Or anything under 1300

I wwas thinking some slim laptops, like ultrabooks

Brands I'm interested in buying:
Toshiba
Samsung
Asus
Let me know what you guys think

(I want the Alienware because it has dual graphic cards)

But if I can get a bigger bang for my buck tell me