Your 7yo Dell is probably a different screen ratio, 16:10, than his which is probably 16:9. You probably have very similar DPIs, but your 1920x1200 monitor just

Your 7yo Dell is probably a different screen ratio, 16:10, than his which is probably 16:9. You probably have very similar DPIs, but your 1920x1200 monitor just has more vertical screen space.