I'm guessing your Publisher document was saved as a picture. If this is the
case, you don't need to change the margins at all. When you insert a
picture in Word, it will be inserted In Line With Text by default and will
be constrained by the page margins. Unless you change all the margins to 0"
(and Word will holler if you do that), you won't be able to expand it to a
full page.
What you should do instead is change the text wrapping to In Front of Text.
Then go to Format Picture and, on the Size tab, change the size to 100%. On
the Layout tab, click Advanced, and set the position as Top relative to Page
and Left relative to Page. This will allow your picture to fill the page.
--
Suzanne S. Barnhill
Microsoft MVP (Word)
Words into Type
Fairhope, Alabama USA
http://word.mvps.org