What is the best pc under $450?

Here you go, 1st build has an NVIDIA GPU

PCPartPicker part list / Price breakdown by merchant

Type Item Price
CPU AMD Athlon X4 860K 3.7GHz Quad-Core Processor $70.99 @ NCIX US
Motherboard Gigabyte GA-F2A58M-HD2 Micro ATX FM2+ Motherboard $35.45 @ SuperBiiz
Memory G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory $59.98 @ OutletPC
Storage Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive $48.60 @ SuperBiiz
Video Card Gigabyte GeForce GTX 750 Ti 2GB WINDFORCE Video Card $109.99 @ Newegg
Power Supply Corsair Builder 500W 80+ Bronze Certified ATX Power Supply $29.99 @ Newegg
Optical Drive Samsung SH-224DB/BEBE DVD/CD Writer $12.99 @ Newegg
Prices include shipping, taxes, rebates, and discounts
Total (before mail-in rebates) $427.99
Mail-in rebates -$60.00
Total $367.99
Generated by PCPartPicker 2015-05-23 20:34 EDT-0400

And here's the AMD GPU build, you can get a second R7 for crossfire, and they're pretty cheap.

PCPartPicker part list / Price breakdown by merchant

Type Item Price
CPU AMD Athlon X4 860K 3.7GHz Quad-Core Processor $70.99 @ NCIX US
Motherboard Gigabyte GA-F2A58M-HD2 Micro ATX FM2+ Motherboard $35.45 @ SuperBiiz
Memory G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory $59.98 @ OutletPC
Storage Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive $48.60 @ SuperBiiz
Video Card Sapphire Radeon R7 260X 2GB Video Card $88.99 @ SuperBiiz
Power Supply EVGA SuperNOVA NEX 750W 80+ Bronze Certified Semi-Modular ATX Power Supply $54.99 @ Newegg
Optical Drive Samsung SH-224DB/BEBE DVD/CD Writer $12.99 @ Newegg
Prices include shipping, taxes, rebates, and discounts
Total (before mail-in rebates) $411.99
Mail-in rebates -$40.00
Total $371.99
Generated by PCPartPicker 2015-05-23 20:39 EDT-0400
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