Alienware Offers Solid-State RAID 0
Solid-state drives have numerous advantages over traditional platter-based drives. They are more durable, they start up faster since there are no platters to spin-up, they offer significantly lower latency than the fastest traditional drives and possibly most important for a notebook, they can survive falls and crashes thanks to their lack of moving parts. With all these advantages, it's not hard to see why you might want one in your notebook.
Solid-state drives aren't without their downfalls however. Unfortunately, solid-state drives are very low capacity by today's standards. Alienware is currently offering a 32GB model, although a RAID 0 configuration would effectively double your capacity to 64GB, that is still pretty low. Luckily Alienware is offering a SSD + 200GB hard drive mix so you'll have space to take your massive pr0n collection with you while you're on the go.
The biggest disadvantage of solid-state drives compared to their mechanical brethren is probably their price. If you want one solid-state drive in your Alienware notebook, be prepared to fork over $500 for the pleasure. The SSD + hard drive option will cost you $620 and the blazing-fast dual-SSD in RAID 0 configuration will cost $920. Also note that the lowest priced Alienware notebook, the Area-51 m5550 only offers the single SDD option. No one said high-tech would be cheap.