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The last time my Windows box crashed (quite some time ago, since I have Vista) I investigated what made it crash and leant from it. Either way, never had any compatibility and/or upgrade problems with Office ever.
OpenOffice and NeoOffice don't have e-mail client, don't have half the features Office 2007 have, take you double as much time to do the same thing in Office 2007 and PowerPoint presentation made with these suits next to PowerPoint 2007 is a shame.
You get what you pay for.