If it's booting into an arcade interface, then it's likely that the applications that you need to replicate that behavior can be found in the Startup directory.
I agree that just replacing the motherboard will do it. If I understand correctly, you want to rebuild it on a different computer. You will need the same MAME version that's on the original. You're also likely to need to come up to speed on the front end that was used.
Essentially, copy the arcade files to the new computer, install the same version of MAME, and install/configure the front end that runs in the Startup.