Don't you see the Preview button at the bottom of the downld section of the search page. In order to preview, you must have downlded at least some % of the file. You can ONLY preview as much as you've downlded!!! If your player isn't working then get xtra codecs or VLC. See the Sticky thread at the top of this section for details.

BTW an old obsolete version of LW will not do you any good. I'm not sure that link even provides genuine LW versions but they may contain viruses/spyware/diallers, etc. Also, many other gnutella clients ban the earlier versions of LW connecting to them.