Hey that’s really nice, good job. Maybe you could do some texture painting on that big machine behind the computer, add some more dark to it and make it a little dirty. Also the lamp looks a little too clean and modern for where it is. Finally could you add some thin wires behind the tubes, I think this would really add to the effect.
The first thing that I’d do is to take my cropping-tools to this picture and cut away everything that isn’t part of the picture, to find “the picture within the picture.” I’d do this for a photo just as I would with CG. I would cut away the dark area on the left side leaving only a slight bit where the angled brace comes up, and likewise cut on the right side up to the innermost 45º angle. Then I would work on the “hidden” lighting – the “non-practical” lighting, in places like the top of the tubes and whatever-it-is that I dimly glimpse in some corridor behind the desk.