Much better! After doing an “Erase and Install” of Mac OS on the new computer, this time I used a complete image backup of the old startup disk (created with SuperDuper), and chose to transfer the stuff at first startup. I let it run all night, and this morning—success! Everything ...
If at first you don’t succeed, curse a blue streak, erase the hard drive and reinstall Leopard, then use Migration Assistant with a full image backup of the old drive, and transfer the settings on the initial startup of the freshly installed OS instead of creating a throwaway account first. ...