I believe you really want to go for about 75+ FPS for it to be good.
from their website:
Minimum requirements: A computer running a Windows 7 or higher, Mac OS 10.8 or higher, or Ubuntu 12.04 LTS operating system, 2 USB ports (at least one powered), and a DVI-D or HDMI graphics output.
Recommended specifications: A desktop computer running a dedicated graphics card with DVI-D or HDMI graphics output, with capability of running current generation 3D games at 1080p resolution at 75fps or higher.
I believe at lower then 75 FPS its easier for people to get nausea from the use of it.
from a Reddit Thread, they recommend a minimum of a GTX 770.
The integrated graphics, may be ok for short testing.
I believe Mike has a Occulus rift, I think he integrated it with his game if I remember correctly, may be thinking of someone else, but I think it was him.