SteamVR Performance Test is a simple benchmark which tests whether your PC has the power to run VR content.
The program can only be downloaded from the Steam client, so you'll need to have a Steam account. If you don't, no problem, signing up is free and easy.
Usage couldn't be any more straightforward. Launch the program via Steam, it runs a two-minute sequence from Valve's Aperture Robot Repair VR demo (which starts dull, but keep watching), and displays its verdict.
The final report lets you know whether your system is fully ready to run high quality VR, can handle low-fidelity content only, or just isn't up to the task at all.
There's only very basic data provided - not even an average frame rate - but the program does at least try to give you some options. If your system seems mostly GPU-bound, for instance, it'll let you know, suggest updating your graphics drivers or upgrading your graphics card.