There's a bug in the LimeWire installer that prevents it from seeing Java 1.4. Even if you have 1.4 installed, it will tell you that it needs 1.3.1. There are a couple of threads further down that explain how to get around it if you have 1.4 installed.

The wheel mouse is not yet supported. The language (Java) now supports the wheel mouse, but LimeWire must be programmed to take advantage of it. I'm not sure when the LW developers will actually implement that piece of it.