The problem with switching products is the money a company loses trying to get their employees used to a new product. At my firm, the average engineer gets paid about 75 dollars an hour. If he or she is bumbling around for two hours trying to get used to a new software, that just cost the company 150 dollars. Multiply that by 30 Engineers, the company just lost 4,500 dollars in the span of two hours. That only has to happen for a few days before the company loses major production time. My company would rather spend 10,000 dollars for a new set of MS licenses than try and switch programs because, in the end, it would be actually cheaper to stick to Microsoft.
I quote this in full because I absolutly agree with that. In an ideal world, every secretary would speak fluent TeX and could change printer toner by herself WITHOUT destroying the thing on every second attempt

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The problem (for which I don't have an easy solution BTW) is because of this "cost of switching" aspect, MS Office gets away with and incredible amount of bugs, inconsistencies and security risks.
For all those people sending around office documents, try hitting ctrl-z a few times next time you open a document someone sent you. It's amazing what you can learn about your clients/suppliers that way. If you're really curious, grab a hex editor.
Or try writing a semi complex (anything with some pics and a few changes in page layout really) 300 page document in Word. Doesn't work. Did not with Word 95, 97, 2000, doesn't with XP. Unblievable. Yet we continue to *work around* the software instead of *with it*, because a switch to something more usefull costs too much.
Another very annoying problem is the closedness of the file formats, eg. for people trying to put together something like a company knowledge base. Huge pain in the neck working with undocumented formats, not doable by any practical means. I really wish I could flick a switch and all of our company docs were XML.
I'm not even starting on the matter of Outlook. Just try to figure out how many man hours are wasted world wide every year because of viral outbreaks.
PS: try Star Office 6, people. It's not perfect (256 MBytes of RAM is a good idea for an average Win2K seat), but if it cost 200$ instead of 0 it would still be better value for money than the MS Office suite.
PS: all IMVHO, of course - but flame away as you wish.