Probably could've gotten the same thing for $200, but I guess $100 isn't a lot to pay to have someone else build it. Doing it yourself is kind of a hassle, but it's definitely worth the savings in my opinion. And it's really not that bad if you know what you're doing.
Back to zircon's situation, so far Hellcom's setup looks like your best option, sans the fancy case and graphics card. Toning those down will probably shave off about $200, but you'll be putting that back into RAM if you want that 4GB (also, I prefer OCZ). I don't think it's likely that you'll find a pre-built with your specs under your $2000 limit. And even if you did, would you pay hundreds of dollars in markup to save yourself a little time?
Also, keep in mind that if noise is an issue, you'll need to spend extra on noiseless fans/heatsinks for your CPU, case, and GPU (although some graphics cards actually already come in noiseless versions). This is kind of a necessity anyway, since it looks like you're intending to overclock.
Good luck on your decision.