as I said in your other thread, you can get a much cheaper socket 939 motherboard. If you like that one, fine... but there are much cheaper ones out there with the same type of specs. I listed one in my other post to you.
You can pair it with whatever CPU you want, but like I mentioned, you might not even need a socket939 board and CPU, depending on what games you want to play.
Subcriminal has the right idea... you can get a SktA motherboard and AthlonXP or Sempron for dirt cheap now, and you'll play a TON of games with that.
To quickly answer your other questions:
- As far as "best" bang for the buck, thats debateable, but the one you listed is overpriced IMHO
-Yes, the ArcadeVGA is still AGP.
- Intel and AMD are both fine, it doesnt really matter. If you were building a top end gaming rig, you would get nice debates from people on both ends... but for a simple MAME machine it doesnt matter. I like AMD personally, so I can never give good opinions on Intel stuff, but either will do fine.