>> . . . That's why I'm leery of its lowering the resolution in its new bigger monitor.<<

Are you talking about the iMac? I don't think they lowered the resolution, it's just lower than a Cinema Display.

>>Still my eyes watered and hurt, and they don't with my Apple screen. Could the problem have been not the resolution but something leaking from the monitor?<<

Maybe some kind of flicker. I can see how a blurry screen might cause you to try to continually focus your eyes and so tire them . . . though I don't know if that's truly an effect of a blurry screen.