Here's a quick conversion tip for all of you considering if you want to run with a horizontal monitor or vertical, and then of what size.

If you choose horizontal, to calculate the "used" screen diagonal for vertical games drawn in the center of the screen, simply do the following:

ActualViewableHorizontalDiagonal * .75 = VerticalGameDiagonalDisplayedInHorizontalMonitor

Therefore, a 19" Computer monitor, having an 18" viewable, yields a 13.5" Vertical picture. (18x.75)

A 21" computer monitor yields 15" Vertical (20x.75)

A 27" TV yields 20.25" Vertical (27x.75)

Remember to take the viewable size not the CRT size.

You can do this in other ways like figuring A^2+B^2 = C^2 and then working backwards with square roots, but it all yields the same: .75 as the multiplier.