opening xml as plain text in MSWord

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Suppose that I have a file foo.TXT whose contents are:
<?xml version="1.0" encoding="UTF-8" ?>
<body />

How can I programmatically (and through the UI) force MSWord (2003 in our
system) to open foo.TXT as plain text, as opposed to noticing that its
contents are XML and trying to show the contents in some fancy way?
.