To tell the truth, neither they are both overpriced in my humble opinion, however if I must choose, then Sony Vaio. Alienware is the epitome of "I had to much money so rather than light my $100's on fire, I bought an alienware". With the Sony Vaio people are only burning $20's....
I will probably get reamed in the arse for saying this but if you are going to buy a laptop I recommend either Toshiba or Dell. I have had a couple Dell laptops and have found their online support to be excellent. They have complete teardown guides with pictures for their laptops so you can safely dismantle them and replace parts yourself, also you can find replacement parts cheap on ebay.
Dry Erase board vs. Chalkboard