Built this one in May 2008:
Case: Antec 900 (with extra optional fans) - $191
Mobo: XFX nVidia n790i Ultra 1333MHz FSB - $559
CPU: Intel Q9550 2.83GHz 1333MHz FSB - $679
RAM: OCZ Reaper 4GB DDR3 1333MHz FSB - $335
GPU: XFX nVidia 9800 GX2 - $829
PSU: Thermaltake Toughpower 1200w - $425
DVD-RW: Asus /w Lightscribe - $40
HDD: 3x WD 2TB Black series + 1x WD 2TB Green (added over time)
Total: $3,008
Monitor: BenQ E2420HD with 2x HDMI, 1x DVI, 1x VGA
Speakers: Logitech Z5500D 5.1 surround.
In May 2010 upgraded to an eVGA nVidia 480GTX ($830) since the GX2 died and generally wasn't that great. Has always been very quick but quite noisy with all those fans.
I'm now looking to build something much quicker but also a lot quieter. In the meantime I've purchased a near-silent HTPC for all non-gaming tasks (such as typing this up) since leaving the gaming PC on all day would leave the ears ringing.
Had a bit of a look around (haven't checked other nearby stores to find the lowest price yet) and am thinking building something like this:
Case: CoolerMaster Silencio 650 - $157
Mobo: Asus P8Z77-V-Deluxe - $308
CPU: Intel i7 3770K 3.5 - 3.9GHz - $338
RAM: Gskill RipjawsZ F3-17000 16GB 2133MHz FSB - $159
GPU: eVGA nVidia GTX 680 4GB 1019MHz O/C edition - $779
PSU: Keep existing? - $0
Optical: Keep Existing? - $0 (or Bluray burner for $89)
HDD: Keep Existing? =$0 (8TB should be enough, might get another SSD though when prices drop more)
CPU Cooler: Haven't looked yet, mustn't block RAM (high profile) and mustn't be noisy
Total so far: $1,879