They don't make their own laptops AFAIK. They buy in shells, just like everyone else. Then the modify/brand those as Alienware. With any make it's important to do some research into the quality of the company's aftersales. There are several customer feedback sites and other resources online. Checking out a supplier in some detail can save hassles later.
From the experiences I've had with Alienware laptops (the one they used to have at the best buy store in town) They do not seem very reliable, every time I went in there I would notice that explorer wasn't running. (though since that laptop was in a public place it was probably heavily abused.) I also have a friend who has an alienware desktop, and has had nothing but problems with it since he got it. When they work they are awesome, but all the experiences I've had, you should just get a Dell.. the XPS is very nice and runs about the same price, and the laptop with the Pentium M chip will allow you to go up to a 128 meg video card, where as last time I checked alienware (two weeks ago) the highest graphics card you could get with their laptop with the Pentinum M, was a 64 meg. Dell however, will charge you about twice as much as alienware for ram, 2 gigs being 600 bucks on alienware, and 1200 on dell. (last I checked.