VR Gaming is rapidly becoming more popular, as the minimum technical requirements have come down, and the components are becoming more powerful. This means a lower required investment into VR Gaming.
However, as with all new technology, we don't always have the best understanding of what we need to get the best performance. VR Gaming is no different. VR requires each "eye" to maintain a steady 90fps, to ensure a smooth experience. VR by nature is imitating a physical world, so maintaining a high framerate is more than desired..it is paramount. Nobody wants to get dizzy or get a headache from playing a VR game.
Knowing the minimum requirements for a new technology like VR can be daunting, especially when there are so many options available. I will hope to alleviate some of your concerns with this system spec.
Most games are fine with an i5 CPU, and VR is no different. You may choose a more powerful i7, but you won't see much difference in gaming (overall system performance will improve however). The i7 will however, allow the GPU to run smoothly and not bottleneck. A 4th gen i5 will work, but a 6th gen i5 will allow for more features, as well as being compatible with the latest motherboards, ram, and SSDs.
Motherboards should be acquired with a decent amount of thought. I prefer ATX boards, as they are easy to work with, allow for lots of features, and are easy to upgrade with. If you chose a 4th gen i5, get a Z97 board. If you went with a 6th gen i5, get a Z170 board. Going with the latest Z series board will enable the best features, as well as any futureproofing.
CPU Cooling is rather personal. Some people prefer air coolers, some would rather run on water. I have been using a Corsair H100i self-contained liquid cooler for about 2 years now, with wonderful results.
RAM & STORAGE
Memory, SSDs, and HDDs are the same as normal gaming requirements. Memory is fine at 8GB, but systems behave better with 16GB (make sure the kit is compatible with your motherboard). SSDs are great to work on. They boot programs exceptionally quick, and use almost no power. HDDs are great for storage, as they are very cheap. A 240GB SSD paired with a 1TB HDD will work fine for VR.
The most important part of VR Gaming, like normal gaming, is the GPU. The VR technology by Oculus and HTC has demanded that some older cards be phased out (for use in VR). The newer modern cards have also reached a very attractive price/performance margin, which allows us to not need a used, older, less effective card.
The RX 480 (reference) from AMD, and the GTX 1060 6GB from Nvidia are great options for VR entrance. The GTX 1060 nearly keeps pace with (or beats) the older GTX 980, which is extremely suprising. The 1060 also uses far less power. The RX 480 comes in about $40 cheaper than the 1060, and the two are neck-and-neck when looking at benchmarks.