Which desktop should I buy? $1000 price range

Hi, I want to buy a desktop, I need some help. I'm getting totally different opinions from every body. I already tried customing building the desktops I found for sale, but the custom built price was more than the prebuilt price! So here are the two I've found

Intel -

Dell - $900
3rd Gen Intel Core i7-3770 processor 3.40 GHz with Turbo Boost 2.0 up to 3.90 GHz
12GB DDR3 SDRAM AT 1600MHZ-2x2GB + 2x4GB
NVIDIA GeForce GT 640 1GB GDDR5
2TB SATA 6Gb/s,7200RPM


AMD - Future Shop - $700
AMD six core Processor FX6100
8GB Ram
2TB HDD
AMD Radeon HD 7570

so, by some I'm told they own systems with way less, and can run games without lag, and then others tell me those systems would barely run games. So everyone is giving me different ideas, could anyone here please help me out? I live in Canada btw, Thanks!