I have an Alienware laptop that I use for gaming and running apps that don't work on Macs. They're really good machines actually (pity about the OS though).
I don't think it's the end of Alienware though because all Dell wants is its profits. It's not making any changes to the structure of the business. Essentially it's exactly the same, only it's under Dell's umbrella now.
Either way, now that they've managed to make Intel Macs boot XP, I've no reason to buy a PC laptop ever again. If I was buying one though, it would definitely be Alienware. (I'd build a desktop by myself)