What should i look for when looking for a Laptop?

I'm going to be buying a computer this weekend and i want to know what i should look for when purchasing.It will be a laptop that is already built and i am will to spend $700. I want to play some games like ARMA and stuff and I want it to still be not out dated in like 2 years from now. Questions are for what parts are most important as to processor ram and graphics card. Usually its a trade off between 4 ram and an i7 and a 6-8 ram with an i5. Plus i don't know much about graphic cards so please explain?