do you already have the x-arcade? because if you don't, please dont use an x-arcade on a cabinet...it is just not cool. i've been there and done that, and it didn't last. no matter what you do, it looks out of place, plus the button layout is less than optimal. i've even went as far as transplanting the x-arcade components into my own panel, which is also a mess because of they way they wire up the controls. they don't use a common ground, and the wires are very short. i am still using the encoder from my x-arcade in my vertical classic cabinet because i didn't have the money to spend on a new one, but as soon as i do, that thing is coming out of there.
if you already have it, then i guess you make do with what you have, but if you haven't already purchased it, please get a real encoder from Ultimarc or GroovyGameGear, and some decent joysticks and buttons (i vote happ or sanwa)
and make sure you post pics of these cabinet.
also, for the monitor, did you already buy it? the reason i ask, is all of these games you wish to emulate were setup for a 4:3 monitor, not a widescreen. so you will end up with either big black bars on either side, or a really stretched image. you may be better off with a non widescreen monitor. for instance, a 20" 16:9 widescreen monitor will display a 16" diagonal 4:3 image. so a 19" non widescreen monitor will give you a larger picture. (technically 19" non widescreen LCDs are 5:4, not 4:3, but it is still better than on a 16:9). i didn't see any on tigerdirect, but newegg.com has a good selection of them. here is one for $139
http://www.newegg.com/Product/Product.aspx?Item=N82E16824254047i have a similar hanns.G model in one of my cabinets and it works great (mine doesn't have internal speakers).
of course, if you already purchased the monitor, it is too late.
I'm not trying to rain on your parade, just trying to let you know there are better options out there if you haven't already purchased this stuff