A listing of download priorities is nice, but there is no ability to boost a more urgent download to the top of the queue short of killing all of the other downloads with higher priority. Unfortunately, when a download is killed, so is the downloaded portion of the file.

OOPS...please disregard.

I found my answer:

Taken from a Tip of the Day
You can tell LimeWire which downloads to start next. Right-click on the column headers in the download area and check the 'Priority' column. Select the download you want to start next and click the up arrow until it's at the top!

...courtesy of default_117 in Feature Requests forum

Thanks,
jroack