Installing OpenOffice.org is a fairly straightforward operation but it may involve some research for Linux newbies (I still count myself to be one) – this is what worked for me on Fedora Core 5 (after downloading the latest version of OpenOffice.org and unpacking the contents of the GZipped archive):
rpm -ivh *.rpm
rpm -ivh openoffice.org-redhat-menus-2.0.3-2.noarch.rpm
After logging out and in again (or by starting a new GUI instance from another console session using startx — :1), the icons should appear on the GNOME Applications menu (in the Office group). Note the use of the Red Hat desktop integration, which, perhaps unsurprisingly, seems to be fine on Fedora too.