Thanks for the replies.
I did try "restoring" each copy of the incomplete file from the recycle bin, but Limewire always started from 0% for each one.

I tried opening up the download.dat file and searching for each occurrance of the incomplete file, there were several entries spread through the file. But I can't understand the hex? data associated with each entry, so this wasn't very edifying.

I also noticed today that in the incomplete directory, the original 55% incomplete file appears to have the word Preview appended to the beginning of its file name.
Any idea why Preview has been added ?
If I was to use rename command to remove the word Preview from the 55% incomplete file, what's the chance that Limewire might recognise it again ?

tia