Here's one build:
Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail
Model #: Nine Hundred
Item #: N82E16811129021
$139.99 -$10.00 Instant $129.99
GIGABYTE GA-P35-DS3R LGA 775 Intel P35 ATX Intel Motherboard - Retail
Model #: GA-P35-DS3R
Item #: N82E16813128050
$129.99 $129.99
EVGA 320-P2-N811-AR GeForce 8800GTS 320MB 320-bit GDDR3 PCI Express x16 HDCP Ready SLI Supported Video Card - Retail
Model #: 320-P2-N811-AR
Item #: N82E16814130082
$279.99 $279.99
CORSAIR CMPSU-620HX ATX12V v2.2 and EPS12V 2.91 620W Power Supply - Retail
Model #: CMPSU-620HX
Item #: N82E16817139002
$189.99 -$20.00 Instant $169.99
Intel Core 2 Quad Q6600 Kentsfield 2.4GHz LGA 775 Processor Model BX80562Q6600 - Retail
Model #: BX80562Q6600
Item #: N82E16819115017
$294.99 $294.99
Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model BL2KIT12864AA804 - Retail
Model #: BL2KIT12864AA804
Item #: N82E16820146565
$109.99 $109.99
Seagate Barracuda 7200.10 ST3320620AS (Perpendicular Recording Technology) 320GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM
Model #: ST3320620AS
Item #: N82E16822148140
$79.99 $79.99
Logitech G11 Silver & Black USB Standard Gaming Keyboard - Retail
Model #: 967929-0403
Item #: N82E16823126009
$58.99 -$5.00 Instant $53.99
Acer AL2216Wbd Black 22" 5ms DVI Widescreen LCD Monitor with HDCP support - Retail
Model #: ET.2216B.0D0
Item #: N82E16824009094
$249.99 -$25.00 Instant $224.99
Logitech G5 2-Tone 6 Buttons 1 x Wheel USB Wired Laser Mouse - Retail
Model #: 931376-0403
Item #: N82E16826104191
$45.99 $45.99
LITE-ON 20X DVD±R DVD Burner With 12X DVD-RAM Write Black SATA Model LH-20A1S - Retail
Model #: LH-20A1S
Item #: N82E16827106057
$34.99 $34.99
Subtotal: $1,554.89
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You could probably shave a little on the case, RAM, mouse, and KB; but you might want to add speakers, another hard drive, or a GTX instead of the GTS. You could also get a e6750 instead of the quad. But hey, this is just one example, and I am sure you'll get a bunch of other good suggestions and can mix and match.