People buy Alienware for the service. They try to keep their customers who all have disposable incomes happy.
I recently bought an ASUS UL50VT, or maybe it was an UL50Vg...
I got it for roughly 500 USD after taxes and shipping and such, and it's been a great buy. Not trying to advertise here, but seriously, it has a dedicated video card and has been able to play anything I throw at it on medium or higher - Starcraft II, TF2, World of Tanks, whatever. It auto-overclocks to 1.73 from 1.30 core2duo, which doesn't sound like much, but clockspeed isn't as important as the 4GB of DDR3 and the 512MB geforce210m.
I'd recommend a laptop with a Radeon Mobility 4650, but those cost a lot more. This thing is fine for gaming on the go and has, I shit you not, up to like 11 hours of battery life if you turn off the dedicated graphics card (it has a switch to go between the two to save power when you're NOT gaming.)
I'd say it's a great overall laptop that you could get 3 of for the price of an alienware. And I looked into the M11x, and it didn't have a DVD burner built-in, and didn't have a numpad keyboard. This thing has a 15.6" screen, too...
I really love this ASUS, as you can see, and even though it's not the most high-powered gaming machine, it does anything I need it to do. I doubt I could run a 2010 release on high graphics, but I can run 2010 releases on medium in 720p (1280x720), or low to medium in the native resolution of 1366x768.