Here are the minimum requirements last I've heard:
http://www.octopusrift.com/building-a-vr-pc/
HTC Vive
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Graphics Card: GeForce GTX 970 or AMD Radeon R9 290 or better
CPU: Intel Core i5 4590 or AMD FX 8350 or greater
RAM: 4GB or more
Video port: HDMI 1.4, DisplayPort 1.2, or better
USB port: 1 USB 2.0 or faster port
Windows 7 SP1 or newer
Oculus Rift
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Graphics Card: GeForce GTX 970 or AMD Radeon R9 290 or better
CPU: Intel Core i5 4590 or greater
RAM: 8GB or more
Video port: HDMI 1.3
USB port: 2 USB 3.0 ports
Windows 7 SP1 or newer
You will probably need to upgrade the CPU to something with at least 4 dedicated cores.