Linda,
From what you are saying, the only thing I can think of is that PageMaker is losing the link to the hi-res file and is printing the 72dpi proxy file.
That would explain the jaggies! Check the Links Manager > File Usage(?)
(Need to check the proper name.)
As far as resizing goes, always do that in the creation package, not in the compositing package. It increases the processing time for the printer and can balloon the file size, particularly if you are doing a multiple set up for business cards.
Ten cards means 10 times that the scaling has to be processed.
Detail / crispness of the original file may be lost.
If you are printing to a desktop, the colour mode is "usually" converted fom RGB to CMYK by the printer software. Check the manual for info on this. If it says so, create your artwork in RGB.
Gonna get to the bottom of this, one way or another. [slick]
Al.