Im in the same boat but with a little more $$
i ended up going for the Mac Book AIR :S (Well went the 2011 comes out his month)
I was gonna get a m14x, but couldnt pull the trigger after owning a M11x
cant wait for the asus ux21, and want something relatively thin.
The new MBA come with sandy bridge, so ill be able to play SC2 on low-medium no problem, which means will be able to play D3 on low-medium.
Im in COMP SCI as well, and wanna start making apps for the iphone and andriod, and kinda cant program for the iphone without a mac.