If you really want a small computer that can handle VR, what about
Zotac's upcoming GTX 980-equipped PC. To be clear, this is using the laptop variant of the desktop GTX 980
not the 980m. I can tell you first-hand that the 980m
does not meet Valve's VR standard (mine scores a 4.7).
My only worry about the Zotac part is... price. Zotac has a similar small PC right now that has a GTX 960 in it (MAGNUS EN970), and it's $800 with a desktop 960 GPU. That "desktop" wording is important, because laptop GPUs are stupidly expensive. The 980m upgrade for my laptop, which includes a replacement heatsink, is between $700-800!

Here's a
real-world example from XoticPC where you can see that there's a $700 price difference between the 980 and the 980m model. To be fair, there are a few other differences, but at most, they may equal up to $200. So, keep in mind that the GTX 980m already costs quite a bit, which is more than the desktop GTX 960 used in the EN970, and now you need to tack $500 onto it.