First, do you have the full Acrobat product, or just the Reader? (The
reader is free, the full product is not). If you have the full
product, when it is installed it creates a couple of "printers" within
Windows. One is called Acrobat PDF Writer, and the other Acrobat
Distiller. To create a PDF file from Word you can select either of the
Acrobat printers as the printer, and send your document to that
printer.

Adobe Acrobat or Acrobat Reader? The former is a fairly expensive program
that you would have had to purchase. The latter is a free download.

I just downloaded something called CutePDF which seems to work well at doing
a basic conversion. It was free and doesn't do pop-ups or cause other junk.
Don't know that it works on the Mac, though.

In Windows, pdf conversion is handled through a printer driver. You may want
to ask on the Mac newsgroup.

Word 98 is on the Mac, not Windows, Do you mean Word 97?

To create a PDF doc, you need a PDF writing program.
To achieve maximum compatibility with Acrobat Reader, I would suggest
getting the full Acrobat product.