Like everyone is saying don't go for Alienware, you can find a laptop with the exact same specs at loads of other places for a fraction of the price. The only thing that makes alienware more expensive is that your paying for the design on their cases and your paying for the logo, that is all.
Example
Alienware Area 51 Desktop $2,760
Intel® Core™ i7 Processor 930 (2.80GHz, 8MB cache, 4.8GT/sec)
English Genuine Windows® 7 Home Premium (64 BIT)
6GB1 Tri-Channel at 1333MHz
1000GB2 SATA hard drive (7200RPM
1.25GB GDDR5 NVIDIA® GeForce® GTX 560 TI
16X DVD+/- RW Optical Drive (DVD & CD read and write)
1 Year Return To Base warranty
Custom built to roughly those specifications from a separate site which specializes in custom building $1,950 Saving $810. You can save even more buying the parts separately and building the PC yourself.
Choice of Coolermaster CM690 II Lite Black OR Coolermaster HAF 912 Case
2 x 120mm Standard Case Fan
Intel Core i7 950 Overclocked To 3.80GHz Per Core CPU
Thermaltake CL-P0564 Frio Ultra Powerful Dual 120mm Fans
Asus P6X58D-E, ATX (USB 3.0, SATA 3.0) Motherboard
Choice of ATI HD6970 2GB OR nVidia GTX 570 1280MB PCI Express Graphics Card
6GB (3 x 2GB) Mushkin PC12800 1600MHz DDR3 Ram
Ultrafast Sandforce 60GB Solid State SATA II For OS & Programs
1000GB SATA II For Data Drive
Integrated 7.1 Channel Audio
22x Dual Layer DVD +/- Re-writer
2 Front + 4 Back Ports
2 x USB 3.0 Ports (On Back)
Choice of Windows: 7 Home Premium OR XP Home With Original CD
Quiet Xilence 800W 4 x PCI-E 135mm Fan PSU
2 Years Return To Base (1st yr. Parts & Labour, 2nd yr. Labour) Warranty