1. save as .doc do not bother with docx, MS Office 2k7 can read .doc format
2. save as .pdf then anyone can read it. this is only viable if he does not need to modify the file.
if those 2 options dont work, then something else is wrong. i have done this more times then i can count and it works 99.9% of the time with the 0.1% being something on the other end. typically user error or windows/office is corrupt on their end.