Torn between upgrading what I have, or building a new computer.

[Sunnday3]

Hello, I have an issue, my computer is somewhat old, and needs to be replaced, but I do not know if the computer I plan to build is a smart Idea, or would upgrading what I have be a better idea?
These are my current specs:
[url]http://pastebin.com/vE6KDvvu[/url]

And for the replacement I plan to use the following parts.
[url]http://pastebin.com/pJ3yEdjV[/url]
[url]http://www.microcenter.com/product/409666/11199-19-20G_AMD_Radeon_HD_7870_GHz_Edition_OC_2048MB_GDDR5_PCIe_30_x16_Video_Card[/url] instead of what I had for a video card in there.

I plan to use this computer for school work as a minor thing, with gaming being the major thing
the most intensive game being crisis 3 and other such benchmarking games, my budget is $500.00

What do I do face punch?

Also if any other info is needed, please ask

[hamar]

You're better off upgrading from scratch. And don't expect to run crysis 3 at a reasonable rate with 500$.

[Sunnday3]

Okay, so from scratch then, what should I change about the list I had made, if anything at all?