Hate to be a bore but for some reason I still can't get the two laptops to see each other. I have made for the firewall to allow them, and changed the settings within the multicast files as you have written in your directions.
I'll outline the steps i took:
-Downloaded and extracted the files to a folder on "Program files"
-Downloaded and extracted the multicast file to a subfolder in that folder
-made firewall exception Squiggle
-Ran the chat messenger program
-Ran the multicast program
-Changed the port and ip settings within the chat program
-Extracted, and ran client program in another system on the same network