Looks very good... I'd thinken the tube that connencts to the chair tho... looks a bit flimsy! Again if this is for construction work, then go for bulky, rather than flimsy
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Maybe ad some handles on those screens, like you see on rack servers!?
RE the glass on the monitors... render an ortho of the glass, just the glass not the entire monitor! give it a solid mat. take that into PS or whatever app you use, and cut the image so it only containes the glass area... make a new layer and give it some grime around the edges and corners... New layer with white color, behind the grime layer... save this as your dirt mask!
Don't know if that was over the top, but you said you never made textures before... make a blended mat, 1 mat glass 2 mat mattblack, and the mask is your new mask!