I can't urge you strongly enough to read the article entitled
How Vista Lets Microsoft Lock Users In. It details how Microsoft has built into Vista the "trusted computing" ability to lock down Office files via DRM such that no unauthorized document reader will be able to decrypt and read them. This is perhaps one of the biggest hidden weapons Microsoft has in its arsenal that could sabotage Linux and OpenOffice.org if Microsoft succeeds in its attempt to plug SUSE and all Novell's "interoperability" bonuses.
Think of this, if you will, as the Tivoization of Office files, only with malicious intent. Microsoft could, indeed, open up the document format completely and swear before God that it will never sue anyone for patent infringement. However, this does not prevent Microsoft from locking Office files in such a way that only Vista users can read them. No one else will be able to do so without the proper authorization, thus rendering the open format and Microsoft compatibility entirely meaningless -- unless, of course, someone agrees to pay Microsoft for the keys to unlock those files.
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