at the beginning of the forum is a thread about how to ask for advice .
But if the price of the OS is included in the build then
PCPartPicker part list:
http://au.pcpartpicker.com/p/xGcjvK
Price breakdown by merchant: http://au.pcpartpicker.com/p/xGcjvK/by_merchant/
CPU: Intel Pentium G3258 3.2GHz Dual-Core Processor ($78.50 @ Centre Com)
Motherboard: ASRock Z97 Anniversary ATX LGA1150 Motherboard ($125.00 @ PCCaseGear)
Memory: G.Skill Sniper 8GB (2 x 4GB) DDR3-1600 Memory ($99.00 @ PCCaseGear)
Storage: Western Digital Caviar Blue 500GB 3.5" 7200RPM Internal Hard Drive ($54.00 @ Centre Com)
Video Card: Asus GeForce GTX 750 Ti 2GB Video Card ($179.00 @ Mwave Australia)
Case: Antec One ATX Mid Tower Case ($69.00 @ Mwave Australia)
Power Supply: Silverstone Strider Essential 500W 80+ Certified ATX Power Supply ($59.00 @ PCCaseGear)
Optical Drive: LG GH24NSB0 DVD/CD Writer ($19.00 @ PCCaseGear)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($115.00 @ Mwave Australia)
Total: $797.50
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-09-18 20:53 EST+1000
Of course its crazy to use Win 7 too . Win 8 is faster , has better features and you can add a start button and set it to act just like 7usi8ng classic shell . You get a better license that lets you use it on two more computers . Win 7 is locked to the first motherboard .
And when windows 9 is released in a few months its likely the upgrade from 7 will be much more expensive