10A is enough for an entire cab? (some of the others are only 6A)
10 amps should be plenty of juice for most applications.
If you really want to get down and dirty about it, just add up the current draw of each device to get the total requirements.
Most CRT monitors are a couple or three amps.
Look on the monitor's info tag, or look up the model of the monitor on the net to get curent draw.
If you're looking at watts, the simple formula I=P/E
Where I=amps, P=watts and E=volts.
Or it may be easier for you to say this amps = watts dived by volts.
This is not exact with AC voltage but it will get you close enough.
Example: A 400 watt computer power supply running on 120 volts AC would be 400/120 = 3.33 amps.
And a computer's power supply is rated for maximum wattage, it doesnt mean that is what it is actually pulling from the AC power line all the time.
Now say if your monitor is rated for 2 amps, then the total draw would be approx 5.3 amps.
Now throw in a marquee lamp, 30 watts or 0.25 amps. (15 watts would be half that)
I think you are getting the picture.
The 6 amp power entry module may be cutting it too close, but Im sure you can find them rated for much higher. At least you know what to look for now.
The entry module I pictured also has a filter to catch incoming noise. This is probably not really necessary for most arcades. You can find them without this filter for a lot less moola.
Edit: or just do what ideft said and hack and old power supply to get it's entry module.