Yeah I Dont "Need" An Operating System lol, and I Was Hoping That Was What I Was Going To Do. So With This Build Ill Be Able To Just Keep Upgrading? and When Upgrading, What Do I Upgrade? The RAM, GFX Card, CPU? I Am Really Aimed At Being A Near Only Call of Duty Player But Some Other FPS/Action Games on The Side.
And Even If I Cant Play At 120FPS, Will I Be Able To Get Above 60?

you dont need 120 fps. 60 is all you need no games run past that. Whoever told you it did is wrong. Yes you could be running it at 120 fps per say, but the game it self is locked at 60. and even once your past 60 it changes nothing it will still look the same either way.

And I May Even Be Able To Budget This Build If It Will Be A Dramatic Help Over The 400 Dollar Build.
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Proclaim wrote you dont need 120 fps. 60 is all you need no games run past that.

Are You Sure About That? I am 100 percent sure that almost all games can run past 60 fps.

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My recommendation for a $500 rig.

Thanks For The Suggestion! But Say I Buy The 400 dollar rig, can i just upgrade ram and video card later?

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My problem with spending less than 5-600USD is that when you want to upgrade to something more heavy duty or overclock you end up having to upgrade most of the stuff you already bought, whereas if you spent more originally you get better value out of it. In any case the Phenom II X4 is a good CPU, shines better when overclocked but the budget doesn't really allow for an overclockable motherboard.

Im_Dalvik wrote And I May Even Be Able To Budget This Build If It Will Be A Dramatic Help Over The 400 Dollar Build.
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Don't go with that, it's very outdated and not what you're looking for.

PCPartPicker part list: [ Register or Signin to view external links. ]
Price breakdown by merchant: [ Register or Signin to view external links. ]
Benchmarks: [ Register or Signin to view external links. ]

CPU: AMD Phenom II X4 965 Black 3.4GHz Quad-Core Processor ($90.98 @ SuperBiiz)
Motherboard: Asus M5A78L-M LX PLUS Micro ATX AM3+ Motherboard ($54.98 @ Outlet PC)
Memory: Crucial Ballistix Sport 4GB (1 x 4GB) DDR3-1600 Memory ($29.99 @ Newegg)
Storage: Western Digital Caviar Blue 500GB 3.5" 7200RPM Internal Hard Drive ($54.49 @ Outlet PC)
Video Card: MSI Radeon HD 7770 GHz Edition 1GB Video Card ($79.99 @ Newegg)
Case: Cooler Master Elite 430 ATX Mid Tower Case ($29.99 @ Newegg)
Power Supply: Corsair Builder 430W 80 PLUS Certified ATX12V Power Supply ($25.99 @ Newegg)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer ($14.99 @ Newegg)
Total: $381.40
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-07-19 14:08 EDT-0400)
So, This Or an Improved Version of This, vs [ Register or Signin to view external links. ]

So
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or
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For Playing Almost Completly CoD at As High a FPS as Possible.