A mobile i7 and a desktop i7 are very different things in terms of performance, same as a mobile 5870 isn't even half as powerful as a desktop 5870. If you ran the game on that laptop lower than the 1920x1080 screen resolution you could max NTW out, but at the native resolution it couldn't do it.
A Gaming laptop needs lots of power to run games, you can only get 1-2 hours on battery so you will either need to charge the battery all the time or play games while plugged into an outlet, either way you gain only minimal portability over a desktop, not to mention it weighs 8lbs. not a light thing to be carrying around.
Another big issue with gaming laptops is they produce a lot of heat which cannot be exhausted very well causing their lifespan to be shortened considerably. That particular laptop is better than the average laptop, but still nowhere near as good as a desktop as far as cooling and system longevity.
If you want the best performance for your money then building one yourself is by far the best way to go, not only will you get 3+ year warranties on the parts themselves, but you save literally hundreds of dollars over buying it prebuilt.
$1,100 would build you a desktop that would be twice as powerful as that laptop, you would still need a screen though, but you could choose a larger screen then you would get on a laptop. Alternatively spending $900 would still get you a superior computer over that laptop.
As far as prebuilt's there's this Dell configuration for nearly $1,300
http://configure.us.dell.com/dellsto...en&s=dhs&cs=19 The motherboard, HDD, RAM and PSU are all of lesser quality in the Dell build than what you could build yourself for that $1,100 though.