To upgrade Openoffice.org from 1.1.x to 2.x, I removed openoffice.org with
yum remove openoffice
Depending on how much space you're willing to sacrifice (openoffice is damn HUGE) you don't need to uninstall the provided one first. The OOo 2.x packages can actually import all the settings from the previous version, so it's even more seamless. Then once the settings have been imported you can remove the older packages to free up a couple hundred megs or so :-P