Make sure you have your chat feature selected in the Tools > Options menu.
Right click on the IP address in the search results window.
If they have chat - it will be in the drop down list of options.
Or - you can type LimeWire 1.7 in the search box and it will bring up all the people with that version.
But some people with 1.7 have that feature disabled by choice.
Some are able to use it - others not, some have double windows or something and end up chatting to themselves.?!?
I've had some success but never found anyone that wanted to chat as yet - it must be the soap I use.
Good Luck