Upgrading JVMs is pretty easy, since there's not much in the way of actual dependencies there. You basically just install the 1.5 JVM, then make things use that instead (usually by removing the old 1.4 installation from your PATH, and adding the 1.5 one). Jorgen's links are of course worth reading for the actual detailed instructions.
In general, package management software normally handles upgrades for you; I'm not particularly familiar with SUSE's offering (yum?) but I'm pretty sure that if you try to install version 1.1 when you have version 1 installed, it'll succeed just fine.