Your problem is still unclear to me, and I am not LimeWire support you know.

The incomplete folder is always re-created when LimeWire starts--but should be empty and take no space after it has been deleted.

To find space on your hard disk, double-click the hard drive, view the window in list mode, then set the view options to calculate all sizes. This will take a while to calculate the sizes of all the folders, but should enable you to see where there is an accumulation of files that you may want to backup to CD/DVD before you delete them.

If most of the space is taken up with the Music folder, use iTunes to burn then delete files.