Well here's how I'd sugest you redesign the navigation system so everything fits:
http://bicostp.gptheatre.co.uk/navtest
I added to the "portable_units.html" page with a "Not-Quite Portables" section, with the MGDp, MVS arcade and MVS console systems in it. (while they are portable, I sugest, for simplicity's sake, that "portable" should only refer to units with built-in screens and power supplies (so MVSp=portable, MDGp doesn't = portable) But that's just me.
I also renamed "portable units" on the navigation bar to "gaming units", to make it a bit more general.
You could add an additional page, but this is not as complicated, and I've already gotten it done. (all that's left to do is make a page for the MS console.)
What do you think?