is that version you want to uninstall installed by rpm? if you install the newest version of mozilla using mozilla's installer, you don't actually need to uninstall your previous version. and i wouldn't suggest uninstalling it either as galeon requires this version of mozilla to run. basically, you're version of mozilla should be installed in /usr/lib/mozilla-1.2.1
while installing the newest version of mozilla (version 1.5) using mozilla's installer will install it in /usr/local/mozilla. the command to run this version is /usr/local/mozilla/mozilla. i myself have 3 versions of mozilla installed with no problems, but i also only use the newest version.
to get java working you may need to upgrade your java version too (1.4.2_01 is the minimum) and follow these directions: