for Arcade Games i really recommend MAME.
youll need atleast a 2.0 GHZ or more is always better to get games such as killer instinct runing, also 1 gig ram or more is always good.
now if your trying to choose the definate version to use use this one its one of the best:
mame32plus http://mameicons.free.fr/mame32p/
and you already mentioned a dedicated cabinet for running emulators then i really recommend
Mamewah http://mamewah.mameworld.net/
even though its very complicated to get the hang of it and youll need to spend a lot of time configuring things out. once you get it all done
you can be launching all your emulators from mamewah
visit www.mameworld.net has lots of useful links to different places
anyways there is this other Frontend to run on your cab and looks pretty decent and i have tried it, the downside is that you have to pay for this front end but if your planning on having a dedicated cabinet for emus then go for it, for easy setup and has better options over mamewah
http://www.maximusarcade.com/
infact am a go ahead and buy that right now
$25 bucks for a nice and easy Frontend.
trust me you quickly find out the hard way that a good Frontend is the way to go if you plan on having other emulators in your cabinet.
but enough about that here is a quick list of the best emus:
SNES - Zsnes
GBA - Visual Boy Advance
NES - Nestopia, Jnes, FCEultra
PC-engine - Magic engine all the way although you have to pay for it it is worth it.
Genesis - Fusion or Gens
Wondeswan - Oswan
NeogeoPocket - Neopop
Arcade - Mame
Playstation - ePSXe or pSX
Playstation 2 - PCSX2
Dreamcast - NullDC or Chankast
Saturn - SSF
N64 - Project64
I know am forgetting some other systems but i spend way too much time with emulators and those i think are the best.:lovin: