Yesterday I played with Open Office 1.1 on my Debian/KDE system. It takes an age to start, and it's quite sluggish when compared with Office2K/NT4 on the same hardware. However, it costs a lot less, and it does what I need - in particular it can export documents to PDF without buying Adobe Acrobat. We converted a MS Word 2K document to OpenOffice format, then made very acceptable PDF, the PDF looked good and had a much smaller file size than the Word original.
OpenOffice, KOffice, et al. may not be perfect yet, but they are very good really, cost nothing, and are as compatible with MS file formats as MS are. We all know how annoying it can be to get an older Word document that Word can't open properly.
OpenOffice makes a very acceptable alternative to an unlicensed copy of Office for the average home user, and in a corporate settings, a significant cost saving.