There is no maximum number of "pages" in a Word document in any version
because there's really no such thing as a "page" in Word, which is not a
page layout application (see http://daiya.mvps.org/wordpages.htm).
There is a limitation of file size (32 MB of text only, excluding graphics)
in versions up through Word 2003. Whether the new XML format of Word 2007
has made any change in this limitation, I don't know, but I do know that, in
previous versions, users have been known to create Word documents of 10,000
pages or more, so there is no real practical limitation on "pages."
Well, let's see. 32Mb is about 32 million bytes, and if a New Page
marker occupies 1 byte, then you could have about 32 million pages, if
there were no other content in the document. (Adjust to taste.)