If you have the full version of Acrobat or one of the free tools (such as
ghostscript) they should have a print driver, which will allow you to print
from any application (including OneNote) into a PDF file.
Thanks very much for the tip! I downloaded GhostScript, and a printer
driver called CutePDF and now have a new "printer" that allows me to print
directly to a PDF file -- very slick!