How big is the difference between a low end $500 build to $600 build? (both with OS)

Hello, this will be my first attempt building a computer and I don't have high standards to game. I've been playing games on a $300 dollar labtop with a broken screen/missing keys that can barely play games such as Witcher 2 and League of Legends at the lowest settings and just want to be able to play games/upcoming games decently on a computer! I have browsed the forums for some low end builds and came across two builds I like, but I don't know how far the 100 dollars will go to boost the performance between the 500 and 600 build. I'm no expert on the builds so any suggestions would be helpful! I have a 720 p monitor, a mouse, and a keyboard. I'm honestly leaning towards the cheaper one since I don't think I can even play any games at 1080 p with my monitor. Thank you for your time!

$500 build :
[PCPartPicker part list](http://pcpartpicker.com/p/QG7v3C) / [Price breakdown by merchant](http://pcpartpicker.com/p/QG7v3C/by_merchant/)

**CPU** | [AMD Athlon X4 760K 3.8GHz Quad-Core Processor](http://pcpartpicker.com/part/amd-cpu-ad760kwohlbox) | $84.73 @ OutletPC
**Motherboard** | [Gigabyte GA-F2A55M-DS2 Micro ATX FM2 Motherboard](http://pcpartpicker.com/part/gigabyte-motherboard-gaf2a55mds2) | $47.98 @ SuperBiiz
**Memory** | [Crucial Ballistix Sport 8GB (2 x 4GB) DDR3-1600 Memory](http://pcpartpicker.com/part/crucial-memory-bls2kit4g3d1609ds1s00) | $77.99 @ Micro Center
**Storage** | [Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive](http://pcpartpicker.com/part/seagate-internal-hard-drive-st1000dm003) | $50.40 @ Amazon
**Video Card** | [MSI Radeon HD 7850 2GB Video Card](http://pcpartpicker.com/part/msi-video-card-r7850twinfrozr2gd5oc) |-
**Case** | [Apex PC-389-C ATX Mid Tower Case](http://pcpartpicker.com/part/apex-case-pc389c) | $29.99 @ Amazon
**Power Supply** | [Corsair Builder 430W 80+ Bronze Certified ATX Power Supply](http://pcpartpicker.com/part/corsair-power-supply-cx430) | $41.27 @ Amazon
**Optical Drive** | [Samsung SH-224DB/BEBE DVD/CD Writer](http://pcpartpicker.com/part/samsung-optical-drive-sh224dbbebe) | $14.99 @ NCIX US
**Operating System** | [Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit)](http://pcpartpicker.com/part/microsoft-os-gfc02050) | $84.98 @ OutletPC
| | **Total**
| Prices include shipping, taxes, and discounts when available | $432.33
| Generated by PCPartPicker 2014-07-27 23:44 EDT-0400 |

$600 build :
[PCPartPicker part list](http://pcpartpicker.com/p/6TGZ99) / [Price breakdown by merchant](http://pcpartpicker.com/p/6TGZ99/by_merchant/)

Type|Item|Price
:----|:----|:----
**CPU** | [AMD Athlon X4 760K 3.8GHz Quad-Core Processor](http://pcpartpicker.com/part/amd-cpu-ad760kwohlbox) | $84.73 @ OutletPC
**Motherboard** | [MSI A78M-E35 Micro ATX FM2+ Motherboard](http://pcpartpicker.com/part/msi-motherboard-a78me35) | $57.99 @ Amazon
**Memory** | [Crucial Ballistix Sport 8GB (1 x 8GB) DDR3-1600 Memory](http://pcpartpicker.com/part/crucial-memory-bls8g3d1609es2lx0) | $74.99 @ Amazon
**Storage** | [Western Digital BLACK SERIES 1TB 3.5" 7200RPM Internal Hard Drive](http://pcpartpicker.com/part/western-digital-internal-hard-drive-wd1003fzex) | $74.49 @ OutletPC
**Video Card** | [Sapphire Radeon R7 260X 2GB Video Card](http://pcpartpicker.com/part/sapphire-video-card-1003662l) | $111.98 @ SuperBiiz
**Case** | [Corsair SPEC-01 RED ATX Mid Tower Case](http://pcpartpicker.com/part/corsair-case-spec01redled) | $45.98 @ Newegg
**Power Supply** | [Antec 450W ATX Power Supply](http://pcpartpicker.com/part/antec-power-supply-vp450) | $37.99 @ Amazon
**Operating System** | [Microsoft Windows 8.1 (OEM) (64-bit)](http://pcpartpicker.com/part/microsoft-os-wn700615) | $89.98 @ OutletPC
| | **Total**
| Prices include shipping, taxes, and discounts when available | $578.13
| Generated by PCPartPicker 2014-07-27 23:54 EDT-0400 |