When you say that you can "certainly bring the data in using Excel", do you
mean that you can automate the process of populating the fields on the .pdf
from with data from Excel.

If that is the case, and the data that you want to use on the form is
presently in a table in a Word document, select that table and then copy it
to the clipboard and then paste it into Excel.

I suspect however that the statement that I quoted above is not really the
case and I do not think that it is something that can be done using
mailmerge in Word.  Googling for AutoFill PDF Form however turns up a number
of leads that claim to do what you want.  One example is

http://www.evermap.com/automailmerge.asp