While I don't pound on office documents all that hard, I do compose documents from time-to-time that require a all-out Office-type application.  I recently have made the transition from OpenOffice.org to [Libre Office](http://www.libreoffice.org/) and I must say that everything (thus far) has been pretty seamless.  I waited quite a while to make the hop over due to the fact that this _did replace_ your OpenOffice.org installation.  Not sure how many hiccups there were at first, but there is nothing but smooth sailing for me.  I've got quite a monster of a "price book" file growing in Calc (one that I will share here when its sorted properly!) and Libre Office seems to be handling it quite well. **Open Source always on that good win.**