FrizzleFried: Thanks so much for the great information and for the hard truth about my monitor.
I am totally OK with accepting that my old monitor has some limitations, and Satan's Hollow seems to be one of only a few games at that resolution -- so I can play that on my PC if I need to.
But regarding trying to optimize the other games, I absolutely can not find any resolutions except 352x288 that will run. I installed mame .106 and ran ArcadeVGARes and none of the 30+ games I had would display with the values that ArcadeVGARes picked for them.
However, if I change the ini files on the games yo 352x288 they display well again.
So, am I limited to 352x288 for every game? Is there another resolution I should try? Most of the games I've been running seem to look pretty good at 352x288: Pac-Man, Frogger, Astro Blaster, 1943 and Pheonix. Gorf displays, but is a little too long.
I understand that different resolutions change the number of pixels that seem to display on my monitor, and I see how that changes the amount of what is shown on the screen. But I really don't understand how to know what resolutions my arcade monitor can show and what resolutions particular games prefer. And I don't understand why when I set the resultion to 352x288, many games appear the same size, but then something like Gorf is super-long. Other than Andy's arcade page, is there somewhere I can look to read up on this?