I custom build all my computers, and generally with a design in mind that won't allow it to be worthless for at least 5 years. Typically my budget is set at a solid $1000, and this works out great now since video cards have come down in price while performance has improved so I generally will shunt the graphics card in favor of more horsepower (since I like to do silly things like break encryptions and game while watching netflix at the same time)
My current rig, built a little over a year ago:
ASUS Crosshair IV Formula - AM3 - AMD 890FX - DDR3 mobo
AMD Phenom II X6 1090T Black Edition Thuban OC'd to 3.92ghz
Corsair CMPSU-750TX 750-Watt TX Series 80 Plus Certified Power Supply
Corsair Cooling Hydro Series H50 - I've never seen my CPU temps budge even under load
Evga GeForce GT 430 1 GB DDR3 PCI-Express 2.0 Graphics Card
Corsair XMS3 8 GB 1333 MHz PC3-10666 240-Pin DDR3
Cooler Master RC-922M-KKN1-GP HAF 922M ATX Mid Tower Case (Black)
OCZ Technology 60 GB Vertex 2 Series SATA II 2.5-Inch Solid State Drive (This has been replaced by the Vertex 3 series since the 2 series crapped out, thank god for their 3 year warranty) - I use this strictly for my Linux/Win7 OS drive, I have roughly 3TB worth of storage drives packed in that I've accumulated over several builds that I used for installing apps and the obvious pr0n.
I run a 24" widescreen and 19" square.. I love running dual, and would love to go dual 24" wides and the 19" "terminal" monitor on the right... god I could multitask like a beast...