Generally with Alienware, you spend alot of money just for the brand name.
Depending on your technical "expertise" id strongly recommend looking into BUILDING your own computer. You can usually get much better specs, for a much lower price.
The RAM for example in that build, theres no need for 16GB ram, 8GB is more than enough for almost anything you will want to run and 1333MHz is lower than the Overclocked RAM you can buy (1600MHz+).
The HDD - check if its 5400RPM or 7200RPM (the higher the better), also check if its SATA II or SATA III (again the higher the better).
Graphics cards, 450's - you could probably fit SLI 560Ti's in on a budget of $1600.
Due to myself being UK based, i cant really put together a build idea for you, but if you check out the "system builder" articles on TOMs, you'll be able to get a rough idea of what you can get for your money.
Also - If you like the idea of building, but arent too sure, check out NewEggs videos on youtube. They do a great 3 part series showing the stages of building from start to finish from selecting components, to building, to installing software and drivers.
As AdrianPerry has said, be aware before buying Alienware that you are paying a few hundred bucks just for an Alien logo.
You'd better build your own rig. You'll be able to buy much better stuff for the same amount of money.
If you take a look at the bestconfigs poll-budget intel gaming pc, any of those configs (for just a thousand bucks) are way better than the Alienware you describe. In fact the first build you can find there but with a x2 GTX 570 SLI (also, a better PSU, still you'd be under 1.5K) would be some kind of monster (Metallica fan, yeap).