Swatwolf I think you went the right way.
I have the Ultimate Arcade II and I temporarily put a 21" Dell Trinitron monitor in it. I took it from my home 'office' setup... I have a 26" LCD HDTV as my primary monitor, and then two black Dell 21" Trinitrons for my other systems... so I just snagged one of the Dells for now.
As big as these guys look upstairs (they make my 17" Nokia look tiny by comparison), they look SMALL in this cab. Once you get a bezel in place the monitor looks too small for the cab.
I'm going to move up to a 27" display which I think is perfect for this particular cabinet. 25" like you are using is also ideal in my opinion... anything smaller and it looks a bit odd to me.
I am soooo jealious right now
