Welcome to the world of Microsoft "compatibility".
Despite their self serving fluff about consistent document formats, every new version of Word has a slightly different "improved" data format, the inner workings of which are proprietary. Old versions of MS Office cannot read documents created in newer versions reliably. Plain documents are usually OK, but complex documents are rarely backward readable.
The reason of course is to force people to do what MS would like to force you to do - upgrade to the latest and greatest version of MSOffice.
To use the much heralded MSOffice 12 will require that you purchase the new Microsoft Vista OS, which in turn will mean that you may well need a new PC since Vista's requirements are not small.
MSOffice 12 is planned to use an open XML document format, but with a twist - it won't be the OASIS Open Document Format agreed upon by a huge majority of players worldwide (Apple, Sun, IBM etc,. etc.). Curiously MS was a member of the orginal consortium that decided on the format, but Microsoft decided instead to go for it's own "improved" version - MSXML
Nominally open, MSXML nevertheless contains proprietary binary extensions which will render it's readability by non-MS applications dodgy to say the least. This is a last desperate attempt by MS to maintain their enforced lock on Office applications and therefore force you to go on buying their overpriced and buggy software.
Ghengis, I'd take this as a fairly distinct wake-up call to say goodbye to Microsoft.
The new OpenOffice.org's OpenOffice 2 is now out and available for free download from
http://www.openoffice.org/ - OpenOffice is completely free to use and install on as many machines as you like.
OpenOffice uses the OASIS OpenDocument XML format by default, but can read, save and create documents in Microsoft formats using reverse engineering techniques. It too may stumble over complex documents, but as you have found out, so do Microsoft's own pricey offerings.
Time to say good bye to the world of Microsoft "compatibility" and get off their gouging upgrade merrygoround I think.
Not only the Commonwealth of Massachusetts but much of the rest of the world is moving towards a truly open and universal data format which is independent of the application used to create of read it, whether this be commercial or open source.
It's just too dangerous to allow one company (already with multiple convictions for abusive and monopolistic acts) to lock up the world's information in it's own proprietary and secret formats.
Edited to add: OpenOffice is of course available for a variety of operating systems:-
Windows
Linux (x86 and PPC)
Solaris (SPARC and x86)
FreeBSD
Mackintosh
So your chum on his mainframe or Mac will use exactly the same program to open your Windows documents and see exectly what you saw. Nice thought (and the way it should be).