You are a lot better building one than pre-built. It's very easy and there are literally hundreds of Youtube videos on how to do so. Here is something I put together for you. That HP will not run Minecraft or any other games very well because there isn't a dedicated video card.
PCPartPicker part list:
http://pcpartpicker.com/p/XKZfD3
Price breakdown by merchant: http://pcpartpicker.com/p/XKZfD3/by_merchant/
CPU: AMD Athlon X4 860K 3.7GHz Quad-Core Processor ($89.99 @ Amazon)
Motherboard: MSI A78M-E45 Micro ATX FM2+ Motherboard ($60.16 @ Newegg)
Memory: G.Skill Ripjaws Series 4GB (1 x 4GB) DDR3-1600 Memory ($37.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($49.49 @ OutletPC)
Video Card: PowerColor Radeon R9 270 2GB TurboDuo Video Card ($99.99 @ Newegg)
Case: Fractal Design Core 1000 USB 3.0 MicroATX Mid Tower Case ($26.99 @ Newegg)
Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply ($54.98 @ OutletPC)
Total: $419.59
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-12-01 15:49 EST-0500
This will destroy Minecraft and many other games. I can't stress it enough, build you're own PC. You'll enjoy it a whole lot more and you'll save money.
Edit: Formatting.