Don't show partials unless at least 1 full is available. Here's why:
 

Take this scenario:

User #1 has a full version of a file.
Users #2, 3, 4, and 5 start downloading that file.
User #1 goes offline, and decides to move that file from his shared directory (maybe to CD to save space).
Users #2, 3, 4, and 5 keep their partials queued, waiting for the full file to come online again.
Users #6 through infinity see the partial hit for their searches and start downloading the partial file.

No one ever gets the full file.

I have had the same 20 partial downloads queued for over 5 weeks now, and no one has ever come online with the full files again. If I do a search, I find plenty of people with the partials. I also see people downloading these partials from me all the time, not knowing that the missing piece will never (apparently) come back onto the network.

The only solution I can see is to not show search results where only a partial file is available. That way, only users #2 through 5 would have wasted their time/bandwidth constantly searching for the particular version of the file that they have partially downloaded. Anyone got a better idea?

-JL