"NVIDIA GTX 970 / AMD 290 equivalent or greater Intel i5-4590 equivalent or greater 8GB+ RAM Compatible HDMI 1.3 video output AMD recommends an eight-core or six-core AMD CPU with a base clock no lower than 3.9GHz, starting at $130 with the AMD FX-6350."
Developers working with the Vive hardware have recommended an Nvidia GTX 980, a step up in performance past the GTX 970. You can run Valve's SteamVR performance test to see if your rig is up to par. A GTX 970 does earn a "ready" mark for the Vive, too."