that 7870 is overpriced. You can get a 7950 for the same price. You can get a phenom ii x4 965 instead and overclock it. edit: wtf, is the 965 d/c'd? I don't see it on newegg and it's $130 on amazon. Just last month I saw it for $80.
they are actually about the same in hardware processing power, the primary difference between this PC and the XBox One is that the XBox One comes with Kinect 2 and this machine doesn't.
sacrificing the video card for more ram is not an issue if comparing it to the XBox One as the One reserves 3 Gigs of its own ram for the OS, so Devs really only have 5 gigs to play with.
The PS4 superior to this build, though, and is also cheaper than the XBox One, but you'll be sacrificing your ability to mod games, and other PC benefits. --- "The easiest way to stop piracy is ... by giving those people a service that's better than what they're receiving from the pirates." ~ Gabe Newell.