What's the file extension of the document he sent you? That's a crucial thing to know.
And, just to be sure, how did you open the document in Outlook Express? I don't think it was File>Open.
I am running Windows XP SP3, my son runs MS Vista. He recently sent me a Word document as an email attachment. When I opened the attachment in Outlook Express, it appeared as a series of letters and squares. Is there any action he or I could take to change this to the original text ?