A $700 computer can run SC2 at max graphics. My computer cost around 1.5k and is 3 years old, and it can run SC2 at max graphics. You are grossly overstating your needs.
There is no way you *NEED* a $2k computer.
Lets have a look at what you want;
1) Smooth gaming
2) Firefox
3) Suite of 'office' programs for homework etc
So what do you require for that?
1) Any graphics card that is mid-top range over the last 3 years, 4gb RAM, at least 2ghz processor, preferably quadcore.
2) A piece of shit that you find on the side of the road can run firefox
3) Anything with internet access can use docs.google, so no problem there
So lets break down the elements you will need;
- Motherboard
- CPU
- Graphics Card
- RAM
- Hard Drive
What Mobo will you need? Well I ain't too flash on Mobos, generally I just ask a guy in a shop wtf I need.
CPU? 2-3ghz quadcore will be fine for you
Graphics? You are going to hear a lot of "NVIDIA > ATI" or vice versa. Really it doesn't matter. You get either and you will notice no difference, all the issues with ATI drivers are in the past, and all the Nvidia issues with woodscrews are in the past. Any card that is later than a 200 series for Nvidia (a 285 or whatever are great), and for ATI, shit I don't even, a 4000 series or later I guess.
RAM? 4gb is fine, 8gb is better.
Hard Drive? Start with half a tb, you can upgrade easily. If you see another drive on special may aswell grab it. You don't need anything special like a Momentus (although you would benefit and they are not that expensive), and you definitely don't need something excessive like an SSD (although ofcourse, you will benefit, though they are prohibitly expensive).
Do not spend $2k on a computer.