The Limewire player isn't very good. We usually recommend making another player your default preview player. But, if that's not working for you, you can make Limewire your default like this:

Tools...options...player...'use Limewire player'

Also, you may find some useful tips in this thread:

http://www.gnutellaforums.com/showthread.php?t=56904

Good Luck

Dan

P.S. You posted in the Phex forum. This is a different p2p software. Keep an eye on where you post.