I thought your pictures looked far better than most I've seen around here. You have the most important things down -- flash off, manual focus, manual shutter (~ 30ms-40ms works for me usually), and tripod. Another trick I learned is to set the MAME pause brightness to 1 instead of .65, and then pause the game when taking a picture to avoid motion blurr. I haven't found a way to avoid the moire pattern, although sometimes it's worse than others.