I'm almost positive that's not a JAMMA cab, so I wouldn't worry about the JPac.
They make a non-Jamma version called the i-pac...
But I agree with Alex, just replace the spade connectors and you're done.
I wouldn't buy anything unless what you have won't work.
Based on what you have and you're level of hackery-desire (I just made that up! :-), I think Windows is a good choice.
(That's not an insult. I didn't say you need a Mac! :-)
Try it with your onboard video first. Soft 15 has some support for some onboard video, so you might get lucky.
I'd try the soft 15 program set at 25Khz first and try that on your monitor.
If there works, then I'd move ahead with the rest of the wiring and software stuff.
The control panel wiring will be the most tedious, but the Video is the most hit/miss in this project.
I used to go to a site called arcadeathome (years ago when I was first working on my cab), but I don't know if it's still there or any good anymore..