just a quick recap for the click-lazy
RAIDMAX SMILODON ATX-612WB
$80
ASRock Z68 Extreme3 Gen3
$121
Intel Core i5-2320
$190
G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600
$47
HIS H667FN1G Radeon HD 6670
$95
Acer G185HVb Black 18.5" 5ms
$90
Cyborg CCB437030002/04/1 Black 3 Programmable Buttons
$38
Consider the 2500k (if you live near a Micro Center brick-and-mortar store), upping mobo to Z77, a cheaper bottom-psu case (better airflow / cooling and 120mm more quiet), use save $ to upgrade GPU:
Part list permalink /
Part price breakdown by merchant /
BenchmarksCPU: Intel Core i5-2500K 3.3GHz Quad-Core Processor ($179.99 @ Microcenter)
Motherboard: Biostar TZ77B ATX LGA1155 Motherboard ($79.99 @ Newegg)
Video Card: PowerColor Radeon HD 6850 1GB Video Card ($134.99 @ NCIX US)
Case: Cooler Master Elite 370 ATX Mid Tower Case ($35.18 @ NCIX US)
Power Supply: Corsair 430W ATX12V Power Supply ($36.98 @ Newegg)
Total: $467.13
(Prices include shipping and discounts when available.)(Generated 2012-04-27 07:24 EDT-0400)You didn't mention a PSU so I threw one in there, PSU calc says 305W recommended, so the 430W should work well. If you have one, make sure it's at least 80+ and / or is "true-rated" +12v @ 250W minimum (and of course more if you are considering upgrading / longevity)
cheers