Alienware is not the best gaming PC. Falcon NW is. But Falcon is a bit more pricey. Do yourself a favor and build your system using
www.newegg.com
You will save a bundle and have a better gaming system for the same price that an Alienware PC would cost you.
If you want a top notch PC though, and dont want to put it together go with Falcon NW. They beat Alienware 2 years in a row in the gaming rig competition.
Hope that helps!