Global Mutiny,

LimeWire is shown in iTunes because it is sharing itself as a playlist. It's not actually adding the files into iTunes -- iTunes just recognizes that there's a shared library (shared by LimeWire) and displays it. That's why you can disconnect, etc...

We haven't yet added a feature to import files into iTunes itself on Windows. That will be there at some point, though...

You can manually do this by highlighting the files or folder in the library in LimeWire and dragging them into iTunes. They'll be copied into iTunes itself.