Limewire Pro just won't run for me

Hi. I just purchased Limewire Pro for Mac OS 10.4 after using Limewire Basic for a few weeks. I am a total computer know-nothing (which is why I own a Mac and not a PC) but I usually can troubleshoot apps myself.
I am using a G4 imac with the "gooseneck" from the round hard drive base to the monitor, running OSX v10.4.11. It has a 1.25 GHz Power PC and 768 MB DDR SDRAM. When I tried to install Limewire Pro, it said it couldn't finish the installation because I need Java 1.5. I tried upgrading Java, and Tiger wouldn't let me. So I tried installing Leopard on this computer (I have Panther on another imac for old
turbotax records which aren't readable by Tiger, and Tiger on another which I don't use for P2P,) and this imac wouldn't let me upgrade to Leopard. The nearest Apple Store is over 140 miles away. I live in the desert in Southern California, and nobody here works on macs. I used Find to locate all Limewire applications, files, Preference folders, Users files, etc. and trashed them and emptied the trash, then reloaded the Pro version and still had the same problem. The Limewire Basic 4.12 with Java 1.42 works okay. I have a satellite internet connection of 512 KBps over the ethernet.
Any advice?
thanks
Monica