Here is my suggestion given your $2,000 budget:
Intel Core i7-920 $289 free shipping
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115202
Motherboard & Memory Combo Deal $464
Mobo - GIGABYTE GA-EX58-UD5 LGA
Memory - CORSAIR DOMINATOR 6GB (3 x 2GB)
http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.290866
Heat Sink/Fan
XIGMATEK Intel Core i7 compatible Dark Knight-S1283V 120mm Long Life Bearing CPU Cooler - Retail $45
http://www.newegg.com/Product/Product.aspx?Item=N82E16835233029
Case
Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail $100
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129021
Power Supply
CORSAIR CMPSU-750HX 750W ATX12V 2.3 / EPS12V 2.91 SLI Ready CrossFire Ready 80 PLUS SILVER Certified Modular Active PFC Power Supply – Retail $160 AR free shipping
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139010
Video Card
EVGA 01G-P3-1180-AR GeForce GTX 285 1GB 512-bit DDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card Retail - $370
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130480
Hard Drives – one for operating system and applications and one for data
Intel X25-M Mainstream SSDSA2M080G2R5 2.5" 80GB SATA II MLC Internal Solid state disk (SSD) – with installation kit Retail $299
http://www.newegg.com/Product/Product.aspx?Item=N82E16820167023
eagate Barracuda 7200.12 ST31000528AS 1TB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive $90
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148433
Optical Drive
Pioneer Black 22X DVD+R 8X DVD+RW 12X DVD+R DL 22X DVD-R 6X DVD-RW 12X DVD-RAM 40X CD-R 32X CD-RW 2MB Cache SATA CD/DVD Burner LabelFlash Support - OEM $35
http://www.newegg.com/Product/Product.aspx?Item=N82E16827129045
OKGEAR 18" SATA II Cable Model GC18AKM – Retail $2
http://www.newegg.com/Product/Product.aspx?Item=N82E16812123160
Total Price $1,941 not including operating system, shipping (where not free) , and taxes
That is a Cadillac and there are a several ways to reduce the cost without significantly affecting basic performance.
Power Supply – this is the modular PSU – you only put inside the cables you need and don’t have extras stuck in there. You can get its non-modular brother for about $60 less. Also note that it is sized to support two graphics cards. If you are sure you will never want those, the PSU could be dropped down to about 500w with additional savings. I just hate to put a smaller on in a system of this caliber. As it is - if you ever want another video card - you can just insert it.
Hard drives – I included a fast solid state drive for the operating system and applications. Don’t know if you know about them – they are good but expensive. You could do without it entirely and just use the other drive – at 1 TB it should take you awhile to fill it. Note that this is the one change that would affect basic performance. Potential savings $299
Total potential savings - $359. Net after savings - $1582.
I tried to give you a starting point – something to work from.
What is your pleasure?
Some additional thoughts.
Regarding cases: I suggest you look at some pictures on newegg.com – or better yet in a store – and pick out one you like. For instance, do you prefer a front door over the drives. Lights?
Regarding performance, you can achieve excellent results at substantially lower cost with the i5 and buget i7 processors. But at your budget level you can also get the i7-920 and a top flight system – which I have shown here.
Regarding the video card, I chose an nVidia card because it has the best processes to use the video card to support certain parallel process calculations – to offload some from the CPU. It requires applications that support it. There are not many right now, but more are writing programs for it.