Alienware tends to be a bit of a ripoff. You could probably get a better laptop for that price, frankly. I've never been a computer person, really (I'm sure it'll surprise a few people), but if you're getting something for gaming I'd stick with a desktop and go through something like Newegg.com. I personally use an
ASUS-N53S laptop for everything and I've been pretty happy with it, though it's more mid range, however I paid significantly less than you would have; mine came out to around $1150 including tax, Canadian.
Definitely avoid MSI. They're cheap, and sometimes have some decent specs, but they're manufactured like shit.