How did you measure your monitor? The reason I ask is because it certainly looks more of a widescreen than a 4:3 ratio monitor. Also Check your scale as the cabinet looks too tall for the distance between the ground and the CP. Those are just my observations though.
Hmm... It would seem that you are onto something. I just checked the model and it seems that some of the measurements were indeed off. It looks quite a bit better now.
BTW, the first picture was taken in perspective mode, which makes the cabinet look much taller. The second picture gives a better idea of what the cab will look like.