Should i get a basic model 15in mac book pro or a alienware m15x with upgraded processor to i7?

Ok well i cant spend more than about 1800 dollars on a laptop but im in between a mbp or an alienware m15x. I play some games like modern warfare 2 but not rly serious. If i get the mbp im gonna keep it all stock adn im going to use boot camp ( i think that's what its called) and also put on windows 7 ultimate with microsoft office. On the alienware i would upgrade it to an i7 processor and it would be 1500 giv or take. the mac is more but i might be able to get a educators discount if i have my uncle do it and we just give him the money and id get a $100 discount. i also like the osx operating system bettr so please giv me answers!