The final image was chosen (the darker image) and I took the picture with a flashlight above the camera aimed down, as I knew I wouldn't be able to simulate the light better than actually lighting the area in the image.
4 images make up the background. The first is what you see in the render. The rest were taken at 3 different exposures (-2, 0, 2) and converted to a real HDR image. The HDR was then used for the indirect lighting in the scene, but I probably could have done without.
The blue box in the image on the right is the simulated monitor geometry converted to a light panel to simulate the lighting that would come from the monitor if the lamp were real.