Aerospace engineer here. From personal experience you won't be doing too much computer-intensive stuff on your own computer. You can of course, but it's not required, since you can go into the computer lab and have desktops that are giong to be better for this kind of stuff.
Still, you want a laptop. OK then. I got this at the beginning of last year: Toshiba Satellite® A665-S6092 16.0" widescreen Laptop
It's a great machine, reliable, powerful, the only marks against it are it's a bit heavy and the battery life isn't long.
As for your preferences...
Don't get an alienware computer. You're paying a premium for a fancy case and a name and it's not worth it. Don't get a mac. You're paying an even bigger premium for a fancy case and a name and it's not worth it. Plus you're not going to be able to run most engineering software in the max OS and you'll need to dual-boot.
With $1500 you can get a beastly machine from a reputable vendor and you can even spring for the customer service or extended warranty if you like. WoW isn't terribly demanding of a game for computers, so anything you get should be fine for it. Don't base your computer decision on that game though - if you're going to a school that has a respectable engineering program at all, you're not going to have much time to play WoW.