Try to find used 2600k + mobo. Then 8GB memory and proper video card. GTX 650 or better is good.
If this need to be new. Then try to build better than this for better price.
http://www.newegg.com/Product/ComboBundleDetails.aspx?ItemList=Combo.1413571
Id put in SSD and intel 3225 good mobo, good psu, and so on. But this budget is too tight to make really good proper build.
Here is my build. No video card but if she needs one then she can buy it later.
PCPartPicker part list:
http://pcpartpicker.com/p/1AzXR
Price breakdown by merchant: http://pcpartpicker.com/p/1AzXR/by_merchant/
Benchmarks: http://pcpartpicker.com/p/1AzXR/benchmarks/
CPU: Intel Core i3-3225 3.3GHz Dual-Core Processor ($132.98 @ Outlet PC)
Motherboard: Asus P8B75-M LX PLUS Micro ATX LGA1155 Motherboard ($69.98 @ Outlet PC)
Memory: A-Data XPG Gaming Series 8GB (1 x 8GB) DDR3-1600 Memory ($59.99 @ Newegg)
Storage: Sandisk Ultra Plus 128GB 2.5" Solid State Disk ($96.86 @ Amazon)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($59.98 @ Outlet PC)
Case: Fractal Design Core 3000 USB 3.0 (Black) ATX Mid Tower Case ($49.99 @ NCIX US)
Power Supply: Rosewill Capstone 450W 80 PLUS Gold Certified ATX12V / EPS12V Power Supply ($59.99 @ Amazon)
Total: $529.77
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-09-06 09:31 EDT-0400)
Sure you can save on MoBo and psu. But is that reliable for anyone? IMO No. Good luck for this build