~$500 computer build for gaming, need advice.

[meitou]

So I just got a job and trying to build a new computer. I want to reuse some of the parts that I bought last year, which are:

PSU - Corsair CX430v2
GPU - EVGA 01G-P3-1361-KR GeForce GTX 460 FPB Video Card - 1024MB, GDDR5, PCI-Express 2.0 (x16), 2x Dual-Link DVI-I, 1x Mini-HDMI, DirectX 11, Dual-Slot, SLI Ready

Approximate Purchase Date: End of this month or next month.

Budget Range: ~500

System Usage from Most to Least Important: gaming.

Are you buying a monitor: No

Parts to Upgrade: CPU, motherboard, RAM, maybe HDD, and case.

Preferred Website(s) for Parts: Newegg, Tigerdirect, amazon.

Location: California

Parts Preferences:
I prefer using Intel CPUs but I would consider a AMD black edition so I can unlock to 6 cores.

Overclocking: No

SLI or Crossfire: No

Your Monitor Resolution:I just bought a Asus VS247H-P which is 1920x1080.
Dual monitoring with Samsung syncmaster 940bw which is 1440x900

And Most Importantly, Why Are You Upgrading: Many programs do not run smoothly, since I currently have a core 2 duo processor computer and 2 gbs of ram, can't really open up multiple applications at once.

 

[Lezli]

This is the build I'm looking at right now:

PCPartPicker part list / Price breakdown by merchant / Benchmarks
CPU: Intel Core i5-3330 3.0GHz Quad-Core Processor ($189.99 @ Newegg)
CPU Cooler: Cooler Master Hyper 212 Plus 76.8 CFM Sleeve Bearing CPU Cooler ($19.99 @ Newegg)
Motherboard: ASRock Z77 Pro3 ATX LGA1155 Motherboard ($84.99 @ Newegg)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory ($64.99 @ Newegg)
Case: Fractal Design Define R4 w/Window (Black Pearl) ATX Mid Tower Case ($93.50 @ Newegg)
Total: $450.46
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-07-20 04:24 EDT-0400)

It seems to fit your price range, although I didn't check to see if you're video card is compatible with this motherboard. If you wanted to fit in a new Hard Disk Drive, you could switch to a cheaper case, as the one I chose is kind of pricey.