Yeah, I kind of figured it was some kind of torrent app or P2P software lol. Um, in LimeWire, there is a tools menu, from thier should be a downloads option. Once you have opened up the downloads options somewhere in thier should be the download location or files location prefferences. Thats what you want. Just moving the folder from drive X to drive Y will not ever solve the issue. Although, I have never tried it, what it might do if you move the Limewire download directory is pormt an error message the next time you run the app. Which could be a good thing, it might have the option to locate the folder right from the error message. This is something I have experience with another program.
So basicly, moving the folder will more then likely not do anything. If you really want to have it download to your F drive, that is something that you configure for Limewires interface it's self.
What I would recomend....
Restart you computer and do not start limewire to assure none of the files in the download folder are in use and cause any problems when moving the folder. Move the Limewire downloads folder to you desired location on you F drive. Then uninstall Limewire. Reinstall but don't race through it. Look for the section or the install were it ask you to specify a download location. Navigate to your F drive, and select the Limewire download folder. Once highlighted hit next on the install window and you should be good to go.