Well you will see Java Version anyway when removing it before installing upgrade, but usually you can in Limewire go to Help-->About Limewire and it will show both Limewire and Java versions.

Also your preference folder (unless you had Limewire for a long time) will just be called Limewire and will be located in Application Data (Hidden Folder)

2 GB Ram ismore than enough to run Limewire and other programs at the same time, so that's not the problem.