Im more or less pissed that there are so many games that arent on there such as return of the jedi, mario brothers, pac land, sub roc, and a bunch of others that came out around the time the others were released.
so get a cheap used P3 computer and update the roms. You could easily add another button in there too. if you redo the control panel, you could prolly move the spinner over a tick, the controller to the left a lil more, then add a Street Fighter button layout, but then you'd be limited to a 1 player cab.
if you kill the giant spinner you could do you controller layout like mine:

hit up craigslist, I saw a P4 3.2 system go for a couple of hundred the other day, with a KB,mouse,monitor,etc
honestly though, for a large portion of the games you dont need that powerful of a processor especially the Street Fighter games and ROTJ