Check out linus on youtube, or his website us.NCIX.com (or just ncix if you're not in the states). He had some crazy custom laptop or two made. I remember one had a nVidia580 card on it. Clunky-as-hell power brick but it was top notch for gaming and watching hi def movies.
Personally I'd say anything that has core i5 processor WITH a decent graphics card (because truth be told you don't need core i7 if your graphics card is good) and 8 gigs of ram will run just about anything smoothly. I don't know of too many games currently that fully utilize that much ram tbh. I do not know much on the AMD side of things, so I'd go with what Q said. He's never lead me wrong when I don't know.
Nothing shouts disappointment like saving up a sizable chunk of cash over the summer meant for a new machine or something, only to have a $1000 car maintenance hit. It's either this now or have it quadruple in the middle of winter.