Patient enough to build a desktop? It takes perhaps two hours your first time. I seriously suggest you go in that direction. Why? Because prebuilt gaming desktops are almost universally horrible options, which cheap out on parts like the power supply, include things like core i7s because they look fancy, even though they don't give you a benefit, and are overpriced.
Seriously, you aren't getting a $700 gaming computer when you buy a prebuilt, you're getting a $550 or $600 gaming computer.
I mean, look at the computer that you yourself linked...
It's got an i3, which is a dual core, and a really puny power supply that won't let you upgrade your graphics hardly at all in the future. It comes with a graphics card that will barely hold its own at 1080p - it's a good card, but cheap.... and they want basically $800 for that!
Now compare that to a custom rig:
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
CPU: Intel Core i5-4430 3.0GHz Quad-Core Processor ($180.49 @ Amazon)
Motherboard: ASRock H87M Pro4 Micro ATX LGA1150 Motherboard ($79.99 @ Micro Center)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory ($67.50 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($56.99 @ NCIX US)
Video Card: EVGA GeForce GTX 760 2GB Video Card ($239.99 @ NCIX US)
Case: Rosewill REDBONE ATX Mid Tower Case ($39.99 @ Amazon)
Power Supply: Corsair CX 600W 80+ Bronze Certified Semi-Modular ATX Power Supply ($44.99 @ Newegg)
Total: $709.94
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-04-12 11:40 EDT-0400)
That's actually AT your budget, so it's cheaper, it has a way better quad core, better RAM, a more reliable hard drive, a WAY better video card, a much higher capacity power supply for future upgrades...
Comparing those two, it should be obvious just how much money is totally wasted when you buy a prebuilt gaming computer.