I have the same problem transfering limewire downloads to itunes. I tried the suggestion above, but it didn't work. It was working perfectly until a couple of days ago. What else could it be or should I try

Something else you need to do for iTunes if you wish them automatically 'Copied' to the iTunes Music Library folder. In iTunes menu bar, Edit menu -> Preferences -> Advanced, check the option for 'Copy files to iTunes Media folder when adding to library'.

And beware of spammed files pretending to be normal audio files: Typical file SIZEs of Spammed Virus files posing as audio files (click on link)