Guild Wars 2

My girlfriend can run around in wvw on medium settings using a quad core with only intel 4000HD graphics.

I am an Acer fanboy, so my recommendation would be something like this: http://www.amazon.com/exec/obidos/ASIN/B00AH4A950/laptopninja-20

I was incredibly surprised at how lightweight GW2 is in terms of system resource use compared to how pretty it looks, but with that system, you should be able to comfortably play GW2 on medium settings without antialiasing (though probably only 30~ FPS in WvW).

Though I will say, unless you 100% need the mobility of a laptop, go for a desktop as you get sooooooooo much more for your money, a $500 desktop can be bought prebuilt online and run almost any game very well. I used to be a hardcore lapto-only person, but since my laptop died, I bought a desktop, cost £400 to make (about $600) and runs everything I could possibly want to play perfectly