Well, the one emaster posted destroys the ones you linked to. AMD unfortunately cannot compete with intel's latest cpus, so the 3770k is about as good as it gets before you get to intels $550 plus monsters. The gtx 680 is also LIGHTYEARS ahead of the 7850. It even comes with more ram, though at a slightly slower speed, but even 8gb is overkill for most situations. Still, for all the extra you are getting, it is definitely worth the extra money. The case is not as nice, but that is something you can forgo to get the upgrades you would be receiving with the more expensive one which will last you a lot longer than the other unit.
As for the power supply, both the 700w and 1000w are likely to be junk oem units that ibuypower includes just as any other company (dell, hp, etc.) would include. They will not actually put out their rated wattages, but that is likely fine since the unit will not pull close to that amount.
http://www.newegg.com/Product/Product.aspx?Item=N82E16883229341
This would be another good option. Slightly cheaper as it uses a slightly slower cpu. However, the benefit of the more expensive cpu is lost on most users since few programs or games can benefit from 8 threads. 7970 is also comparable to the 680, though I think the 680 is the better card as well. Still a great build, though not as good of a deal as the other system.
I would actually just configure my own system from ibuypower:
http://www.ibuypower.com/Store/Intel_Z77_Core_i5_Configurator
This allows you to choose some better equipment for the price, especially a quality power supply.
Doing a quick configure with:
3570k cpu
asrock extreme 4 motherboard
2x4gb ddr3 1600 ram
120gb ssd
2tb 7200 hdd
750W corsair TX V2
gtx 670
CoolerMaster Haf 922
The addition of an ssd is a great upgrade which vastly speeds up the system in load times and responsiveness. The biggest single upgrade you can make to any system using a mechanical hard drive.
A gtx 670 and a 3570k really are all you will need for performance. The additional cost of the 3770k and 680 is not worth the increased performance.
The 750W TX V2 from corsair is a great unit that will be a HUGE improvement over the junk psu in those prebuilts on newegg. There is a reason that it costs $20 more than ibuypowers standard 1000w unit.
The motherboard is likely a big improvement with additional features such as more usb 3.0 ports and sli support. You may not need it, but it doesn't hurt to have. It also a better motherboard and highly recommended at its price point.
I put in a solid case, but the site gives you some decent options to choose from. Have a look at what peaks your interest. You could even go with a budget case like the NZXT Gamma which will shave another $40 off.
The way I configured it, it came in just over $1400.
