So you have a non-overclocked i7-2600k, stock CPU cooler, unknown motherboard (P67 or Z68 hopefully), 16GB of DDR3-1600 memory (overkill), 2TB hard drive (hopefully Seagate or Samsung), BD reader / DVD-RW, unknown PSU, and a pair of HD 6770 GPUs. For $1600 you can do a lot better building it yourself.... like maybe three times the GPU muscle, the addition of a good SSD boot drive, and an aftermarket CPU cooler for a smooth 4.5GHz overclock. Prebuilt I can't give you a price comparison with, but I would suspect that is still a little high.
Two HD 6770 GPUs in crossfire will act as one and scale to almost double the power as a single HD 6770. You can also run them individually if you need more monitor support.
Ignoring price, that's a nice system. Most gamers would have gotten a smaller cpu and much stronger graphics at that price. However this is a nice all around system.
"since it has 2 graphics cards does that mean twice as powerful in games with 1 monitor?" You see a strong benefit with two vs one video card, however it's not 2X. You also want to keep the video driver current -- some games have problems when using two video cards. The fixes show up in the video driver service stream.