Making Word documents really read-only
Tech Forum - Dr. Nitin Paranjape
"The only way to duplicate this document and make changes to it is to visually see the original document and re-type all the text and formatting! Of course this can be done but it is so much more difficult now!"

Actually no, there's a very easy way to get around this and it doesn't require a degree in programming or a "brute-force" password crack, in fact you don't have to know the password at all. It's so easy, anyone could do it.

In fact I challenge anyone to find me a document (.doc or .rtf format) that cannot be edited within minutes.

For this reason, the only truly effective way to protect your documents is to PDF them.