You first need to be sure chat is enabled. Tools>Options>Chat. Also right-click the top of the columns of either or both the search results & download & upload windows & choose to show chat. A chat column will appear which will show if another user has chat enabled. A small yellow smiley chat icon will appear if they do have it enabled. Then right-click them & choose chat. But one of the problems with chat is many people are away from the computer (at school/work/asleep) or have LW hidden in background whilst they do something else. So the chat becomes stale before they see it. AFAIK Other non-LW (or LW code based) clients don't show the chat icon but still might be able to chat. I don't believe I've ever chatted with another gnutella client though so I'm not sure they use the same chat protocol. But AFAIK LW's chat technology hasn't changed in many years. Possibly since it was introduced the very first time with one of the very early versions. The only change I've noticed about chat since is no chat buttons & a slightly different chat interface which happened about a year ago I think.