I would recommend avoiding Alienware also. I don't have any problem with the PCs they build I just think they are overpriced. You can build a PC on their website then build an identical PC at almost any other company for less. Unless you think that alien head on the case is sexy enough to justify the cost.
I have used ibuypower in the past for a laptop and they delivered a machine that ran flawlessly for 3 years until it got knocked off a desk and broke the screen. Their customer support was also very helpful when I called. I have to say was helpful as I haven’t used them in about 2 years. Their prices are also very competitive. They have a feature on their customization screen that will show you the potential frame rates on max settings for the game you would like to play most. I'm sure other companies have something similar to this on their page I just know for a fact ibuypower has it.
As others have said you will get the most bang for your buck if you build it yourself.
If you decide to build it yourself do decent amounts of research on your items to help avoid some of the buyer's remorse that I had when I purchased the initial graphics card for my system. You can look up almost any PC part at cnet.com for a review of the item in question and on some products they even include benchmark results.
There is also the option to use a barebones kit. With these all the parts you need are included in a bundle. You just have to put it together. Which can help reduce some of the stress picking out all the parts. Usually an Operating System is not included with these packages so check to make sure it either comes with one or you purchase one when you order. Building a computer isn't the scary task that it used to be and you have Kaolian for all your troubleshooting needs.
For about half your budget you can build a system that will preform everything your'e asking for. If you spend the full $2,000 you should be good for a while.
20 minutes later I notice the original post was 2 weeks ago.
Edited, Nov 17th 2011 11:01am by xinaskin