Running the text-based installer, install-updates script, from RedHat Updates CD results in dependancies error going from 6.0 (Hedwig) to 7.0: Testing system for dependency problems... RPM reported a problem while testing: error: failed dpendencies: libqimgio.so.0 is needed by kdebase-1.1.2-11
Looks like a package ordering problem in the installer - it should have noticed that kdebase-1.1.2-48 (which is newer than 1.1.2-11 and doesn't need qimgio) should be installed.
You can work around this by chosing the kdebase package as well.