Alienwares suck, I've had horrible experience with them. They are basically the Apple of PC's. Why? Because they're overpriced pieces of **** that blue screen on you and get extremely hot. IMO MSI, Sager and CyberPower PC's have really good reputation from they're customers. Personally I built my Gaming PC, Watercooled it, and managed to do all of that for less than $1500. Currently I use a RMBP for SC2, and I play at 1650X1050 on Ultra and I get 84FPS, but the lowest FPS was when I had a massive battle and it went to 54FPS. Seriously though, you could just get a regular MBP 15 inch with the GTX 650M 1GB VRAM and be Okay for SC2. It's really not a graphic intensive game.
If you want Windows then get a MSI laptop, Sager or CyberPower PC laptop. These brands have good reputation and I can personally recommend them (a bunch of my friends own various models).