First, in order to open a Word document they have to either have Word
installed on their system or at least the Word Viewer:
http://www.microsoft.com/office/000/viewers.asp
This is true of any file you attach, it cannot be opened on another setup
unless the recipient has an application compatible with that file or has the
application in which it was created.
Second, if they are receiving it in Outlook Express, they should go to
Tools, select options, go to the Security tab, remove the check from "Do not
allow attachments to be saved or opened that could potentially be a virus,"
click apply and ok. Note: before opening any file attachment, it should
first be saved elsewhere and scanned for viruses before opening. This is
true even of files coming from people they know including you as generally
users do not know when they are infected and viruses propagate by sending
themselves to all the addresses in a user's address book.
Third, if they are receiving the attachment through a webmail account, they
need to check their options to see if they are blocking attachments.
